diff --git a/README.md b/README.md
index 8da667ec1..68c8bc5ba 100644
--- a/README.md
+++ b/README.md
@@ -1,29 +1,29 @@
-# OpenAPI-diff 
+# OpenAPI-diff
 
 Compare two OpenAPI specifications (3.x) and render the difference to HTML plain text, Markdown files, or JSON files.
 
-[![Build](https://github.com/OpenAPITools/openapi-diff/workflows/Main%20Build/badge.svg)](https://github.com/OpenAPITools/openapi-diff/actions?query=branch%3Amaster+workflow%3A"Main+Build")
-[![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=OpenAPITools_openapi-diff&metric=alert_status)](https://sonarcloud.io/dashboard?id=OpenAPITools_openapi-diff)
+[Build](https://github.com/OpenAPITools/openapi-diff/actions?query=branch%3Amaster+workflow%3A"Main+Build")
+[Quality Gate Status](https://sonarcloud.io/dashboard?id=OpenAPITools_openapi-diff)
 
-[![Maven Central](https://img.shields.io/maven-central/v/org.openapitools.openapidiff/openapi-diff-core)](https://search.maven.org/artifact/org.openapitools.openapidiff/openapi-diff-core)
+[Maven Central](https://search.maven.org/artifact/org.openapitools.openapidiff/openapi-diff-core)
 
-[![Contribute with Gitpod](https://img.shields.io/badge/Contribute%20with-Gitpod-908a85?logo=gitpod)](https://gitpod.io/#https://github.com/OpenAPITools/openapi-diff)
-[![Join the Slack chat room](https://img.shields.io/badge/Slack-Join%20the%20chat%20room-orange)](https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g)
+[Contribute with Gitpod](https://gitpod.io/#https://github.com/OpenAPITools/openapi-diff)
+[Join the Slack chat room](https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g)
 
-[![Docker Automated build](https://img.shields.io/docker/automated/openapitools/openapi-diff)](https://hub.docker.com/r/openapitools/openapi-diff)
-[![Docker Image Version](https://img.shields.io/docker/v/openapitools/openapi-diff?sort=semver)](https://hub.docker.com/r/openapitools/openapi-diff/tags)
+[Docker Automated build](https://hub.docker.com/r/openapitools/openapi-diff)
+[Docker Image Version](https://hub.docker.com/r/openapitools/openapi-diff/tags)
 
 # Requirements
 
-* Java 8
+- Java 8
 
 # Feature
 
-* Supports OpenAPI spec v3.0.
-* In-depth comparison of parameters, responses, endpoint, http method (GET,POST,PUT,DELETE...)
-* Supports swagger api Authorization
-* Render difference of property with Expression Language
-* HTML, Markdown, Asciidoc & JSON render
+- Supports OpenAPI spec v3.0.
+- In-depth comparison of parameters, responses, endpoint, http method (GET,POST,PUT,DELETE...)
+- Supports swagger api Authorization
+- Render difference of property with Expression Language
+- HTML, Markdown, Asciidoc & JSON render
 
 # Maven
 
@@ -38,11 +38,13 @@ Available on [Maven Central](https://search.maven.org/artifact/org.openapitools.
 ```
 
 # Homebrew
+
 Available for Mac users on [brew](https://formulae.brew.sh/formula/openapi-diff)
 
 ```bash
 brew install openapi-diff
 ```
+
 Usage instructions in [Usage -> Command line](#command-line)
 
 # Docker
@@ -211,6 +213,7 @@ ChangedOpenApi diff = OpenApiCompare.fromLocations(oldSpec, newSpec, null, optio
 ### Render difference
 
 ---
+
 #### HTML
 
 ```java
@@ -500,7 +503,8 @@ openapi-diff is released under the Apache License 2.0.
 
 # Thanks
 
-* Adarsh Sharma / [adarshsharma](https://github.com/adarshsharma)
-* Quentin Desramé / [quen2404](https://github.com/quen2404)
-* [Sayi](https://github.com/Sayi) for his project [swagger-diff](https://github.com/Sayi/swagger-diff) 
-  which was a source of inspiration for this tool
+- Adarsh Sharma / [adarshsharma](https://github.com/adarshsharma)
+- Quentin Desramé / [quen2404](https://github.com/quen2404)
+- [Sayi](https://github.com/Sayi) for his project [swagger-diff](https://github.com/Sayi/swagger-diff) 
+which was a source of inspiration for this tool
+
diff --git a/cli/src/main/java/org/openapitools/openapidiff/cli/Main.java b/cli/src/main/java/org/openapitools/openapidiff/cli/Main.java
index 85f125d78..421b543e4 100644
--- a/cli/src/main/java/org/openapitools/openapidiff/cli/Main.java
+++ b/cli/src/main/java/org/openapitools/openapidiff/cli/Main.java
@@ -22,6 +22,7 @@
 import org.openapitools.openapidiff.core.output.AsciidocRender;
 import org.openapitools.openapidiff.core.output.ConsoleRender;
 import org.openapitools.openapidiff.core.output.HtmlRender;
+import org.openapitools.openapidiff.core.output.I18n;
 import org.openapitools.openapidiff.core.output.JsonRender;
 import org.openapitools.openapidiff.core.output.MarkdownRender;
 import org.slf4j.Logger;
@@ -143,6 +144,13 @@ public static void main(String... args) {
             .argName("file")
             .desc("export diff as json in given file")
             .build());
+    options.addOption(
+        Option.builder()
+            .longOpt("lang")
+            .hasArg()
+            .argName("language")
+            .desc("output language (en, zh-Hant, zh-CN). Default: en")
+            .build());
 
     // create the parser
     CommandLineParser parser = new DefaultParser();
@@ -155,9 +163,13 @@ public static void main(String... args) {
       }
       if (line.hasOption("version") || line.hasOption("v")) {
         String version = Main.class.getPackage().getImplementationVersion();
-        System.out.println("openapi-diff version: " + (version != null ? version : "DEV"));
+        System.out.println(
+            I18n.getMessage("cli.version.prefix") + " " + (version != null ? version : "DEV"));
         System.exit(0);
       }
+      if (line.hasOption("lang")) {
+        I18n.setLocale(I18n.parseLocale(line.getOptionValue("lang")));
+      }
       String logLevel = "ERROR";
       if (line.hasOption("off")) {
         logLevel = "OFF";
@@ -185,10 +197,7 @@ public static void main(String... args) {
             && !logLevel.equalsIgnoreCase("WARN")
             && !logLevel.equalsIgnoreCase("ERROR")
             && !logLevel.equalsIgnoreCase("OFF")) {
-          throw new ParseException(
-              String.format(
-                  "Invalid log level. Expected: [TRACE, DEBUG, INFO, WARN, ERROR, OFF]. Given: %s",
-                  logLevel));
+          throw new ParseException(I18n.getMessage("cli.invalid.log.level", logLevel));
         }
       }
       if (line.hasOption("state")) {
@@ -199,7 +208,7 @@ public static void main(String... args) {
       root.setLevel(Level.toLevel(logLevel));
 
       if (line.getArgList().size() < 2) {
-        throw new ParseException("Missing arguments");
+        throw new ParseException(I18n.getMessage("cli.missing.arguments"));
       }
       String oldPath = line.getArgList().get(0);
       String newPath = line.getArgList().get(1);
@@ -223,7 +232,8 @@ public static void main(String... args) {
         for (String propKeyAndVal : configProps) {
           String[] split = propKeyAndVal.split(":");
           if (split.length != 2 || split[0].isEmpty() || split[1].isEmpty()) {
-            throw new IllegalArgumentException("--config-prop unexpected format: " + propKeyAndVal);
+            throw new IllegalArgumentException(
+                I18n.getMessage("cli.config.prop.unexpected.format") + " " + propKeyAndVal);
           }
           optionBuilder.configProperty(split[0], split[1]);
         }
@@ -283,12 +293,13 @@ public static void main(String... args) {
       }
     } catch (ParseException e) {
       // oops, something went wrong
-      System.err.println("Parsing failed. Reason: " + e.getMessage());
+      System.err.println(I18n.getMessage("cli.parsing.failed") + " " + e.getMessage());
       printHelp(options);
       System.exit(2);
     } catch (Exception e) {
       System.err.println(
-          "Unexpected exception. Reason: "
+          I18n.getMessage("cli.unexpected.exception")
+              + " "
               + e.getMessage()
               + "\n"
               + ExceptionUtils.getStackTrace(e));
diff --git a/core/src/main/java/org/openapitools/openapidiff/core/output/AsciidocRender.java b/core/src/main/java/org/openapitools/openapidiff/core/output/AsciidocRender.java
index 895838472..f439ecf6e 100644
--- a/core/src/main/java/org/openapitools/openapidiff/core/output/AsciidocRender.java
+++ b/core/src/main/java/org/openapitools/openapidiff/core/output/AsciidocRender.java
@@ -46,7 +46,7 @@ public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
               diff.getNewSpecOpenApi().getInfo().getVersion()));
       safelyAppend(outputStreamWriter, System.lineSeparator());
       safelyAppend(outputStreamWriter, System.lineSeparator());
-      safelyAppend(outputStreamWriter, "NOTE: No differences. Specifications are equivalent");
+      safelyAppend(outputStreamWriter, I18n.getMessage("note.no.differences"));
     } else {
       safelyAppend(
           outputStreamWriter,
@@ -63,13 +63,13 @@ public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
       safelyAppend(outputStreamWriter, System.lineSeparator());
 
       List<Endpoint> newEndpoints = diff.getNewEndpoints();
-      listEndpoints(newEndpoints, "What's New", outputStreamWriter);
+      listEndpoints(newEndpoints, I18n.getMessage("whats.new"), outputStreamWriter);
 
       List<Endpoint> missingEndpoints = diff.getMissingEndpoints();
-      listEndpoints(missingEndpoints, "What's Deleted", outputStreamWriter);
+      listEndpoints(missingEndpoints, I18n.getMessage("whats.deleted"), outputStreamWriter);
 
       List<Endpoint> deprecatedEndpoints = diff.getDeprecatedEndpoints();
-      listEndpoints(deprecatedEndpoints, "What's Deprecated", outputStreamWriter);
+      listEndpoints(deprecatedEndpoints, I18n.getMessage("whats.deprecated"), outputStreamWriter);
 
       List<ChangedOperation> changedOperations = diff.getChangedOperations();
       ol_changed(changedOperations, outputStreamWriter);
@@ -78,8 +78,8 @@ public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
       safelyAppend(
           outputStreamWriter,
           diff.isCompatible()
-              ? "NOTE: API changes are backward compatible"
-              : "WARNING: API changes broke backward compatibility");
+              ? I18n.getMessage("note.backward.compatible")
+              : I18n.getMessage("warning.broke.compatibility"));
       safelyAppend(outputStreamWriter, System.lineSeparator());
     }
     try {
@@ -94,7 +94,7 @@ private void ol_changed(
     if (null == operations || operations.isEmpty()) {
       return;
     }
-    safelyAppend(outputStreamWriter, title("What's Changed", 2));
+    safelyAppend(outputStreamWriter, title(I18n.getMessage("whats.changed"), 2));
     safelyAppend(outputStreamWriter, System.lineSeparator());
     for (ChangedOperation operation : operations) {
       String pathUrl = operation.getPathUrl();
@@ -105,30 +105,33 @@ private void ol_changed(
       safelyAppend(outputStreamWriter, itemEndpoint(method, pathUrl, desc));
       safelyAppend(outputStreamWriter, System.lineSeparator());
       if (result(operation.getOperationId()).isDifferent()) {
-        safelyAppend(outputStreamWriter, "* Operation ID:");
+        safelyAppend(outputStreamWriter, "* " + I18n.getMessage("operation.id") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(
             outputStreamWriter,
             String.format(
-                "** Changed %s to %s",
-                operation.getOperationId().getLeft(), operation.getOperationId().getRight()));
+                "** %s %s %s %s",
+                I18n.getMessage("action.changed"),
+                operation.getOperationId().getLeft(),
+                I18n.getMessage("to"),
+                operation.getOperationId().getRight()));
         safelyAppend(outputStreamWriter, System.lineSeparator());
       }
       if (result(operation.getParameters()).isDifferent()) {
-        safelyAppend(outputStreamWriter, "* Parameter:");
+        safelyAppend(outputStreamWriter, "* " + I18n.getMessage("parameter") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(outputStreamWriter, ul_param(operation.getParameters()));
         safelyAppend(outputStreamWriter, System.lineSeparator());
       }
       if (operation.resultRequestBody().isDifferent()) {
-        safelyAppend(outputStreamWriter, "* Request:");
+        safelyAppend(outputStreamWriter, "* " + I18n.getMessage("request") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(
             outputStreamWriter, ul_content(operation.getRequestBody().getContent(), true, 2));
         safelyAppend(outputStreamWriter, System.lineSeparator());
       }
       if (operation.resultApiResponses().isDifferent()) {
-        safelyAppend(outputStreamWriter, "* Return Type:");
+        safelyAppend(outputStreamWriter, "* " + I18n.getMessage("return.type") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(outputStreamWriter, ul_response(operation.getApiResponses()));
         safelyAppend(outputStreamWriter, System.lineSeparator());
@@ -142,13 +145,15 @@ private String ul_response(ChangedApiResponse changedApiResponse) {
     Map<String, ChangedResponse> changedResponses = changedApiResponse.getChanged();
     StringBuilder sb = new StringBuilder();
     for (String propName : addResponses.keySet()) {
-      sb.append(itemResponse("** Add ", propName));
+      sb.append(itemResponse("** " + I18n.getMessage("action.add") + " ", propName));
     }
     for (String propName : delResponses.keySet()) {
-      sb.append(itemResponse("** Deleted ", propName));
+      sb.append(itemResponse("** " + I18n.getMessage("action.deleted") + " ", propName));
     }
     for (Entry<String, ChangedResponse> entry : changedResponses.entrySet()) {
-      sb.append(itemChangedResponse("** Changed ", entry.getKey(), entry.getValue()));
+      sb.append(
+          itemChangedResponse(
+              "** " + I18n.getMessage("action.changed") + " ", entry.getKey(), entry.getValue()));
     }
     return sb.toString();
   }
@@ -165,7 +170,9 @@ private String itemResponse(String title, String code) {
 
   private String itemChangedResponse(String title, String contentType, ChangedResponse response) {
     return itemResponse(title, contentType)
-        + "** Media types:"
+        + "** "
+        + I18n.getMessage("media.types")
+        + ":"
         + System.lineSeparator()
         + ul_content(response.getContent(), false, 3);
   }
@@ -176,15 +183,19 @@ private String ul_content(ChangedContent changedContent, boolean isRequest, int
       return sb.toString();
     }
     for (String propName : changedContent.getIncreased().keySet()) {
-      sb.append(itemContent("Added ", propName, indent));
+      sb.append(itemContent(I18n.getMessage("action.added") + " ", propName, indent));
     }
     for (String propName : changedContent.getMissing().keySet()) {
-      sb.append(itemContent("Deleted ", propName, indent));
+      sb.append(itemContent(I18n.getMessage("action.deleted") + " ", propName, indent));
     }
     for (String propName : changedContent.getChanged().keySet()) {
       sb.append(
           itemContent(
-              "Changed ", propName, indent, changedContent.getChanged().get(propName), isRequest));
+              I18n.getMessage("action.changed") + " ",
+              propName,
+              indent,
+              changedContent.getChanged().get(propName),
+              isRequest));
     }
     return sb.toString();
   }
@@ -201,8 +212,11 @@ private String itemContent(
       boolean isRequest) {
     StringBuilder sb = new StringBuilder();
     sb.append(itemContent(title, contentType, indent))
-        .append(itemContent("Schema:", "", indent))
-        .append(changedMediaType.isCompatible() ? "Backward compatible" : "Broken compatibility")
+        .append(itemContent(I18n.getMessage("schema") + ":", "", indent))
+        .append(
+            changedMediaType.isCompatible()
+                ? I18n.getMessage("backward.compatible")
+                : I18n.getMessage("broken.compatibility"))
         .append(System.lineSeparator());
     if (!changedMediaType.isCompatible() && changedMediaType.getSchema() != null) {
       sb.append(incompatibilities(changedMediaType.getSchema()));
@@ -221,13 +235,17 @@ private String incompatibilities(String propName, final ChangedSchema schema) {
     }
     if (schema.isCoreChanged() == DiffResult.INCOMPATIBLE && schema.isChangedType()) {
       String type = type(schema.getOldSchema()) + " -> " + type(schema.getNewSchema());
-      sb.append(property(propName, "Changed property type", type));
+      sb.append(property(propName, I18n.getMessage("changed.property.type"), type));
       sb.append(System.lineSeparator());
       sb.append(System.lineSeparator());
     }
     String prefix = propName.isEmpty() ? "" : propName + ".";
     sb.append(
-        properties(prefix, "Missing property", schema.getMissingProperties(), schema.getContext()));
+        properties(
+            prefix,
+            I18n.getMessage("missing.property"),
+            schema.getMissingProperties(),
+            schema.getContext()));
     schema
         .getChangedProperties()
         .forEach((name, property) -> sb.append(incompatibilities(prefix + name, property)));
@@ -286,26 +304,34 @@ private String ul_param(ChangedParameters changedParameters) {
     List<ChangedParameter> changed = changedParameters.getChanged();
     StringBuilder sb = new StringBuilder();
     for (Parameter param : addParameters) {
-      sb.append(itemParam("** Add ", param));
+      sb.append(itemParam("** " + I18n.getMessage("action.add") + " ", param));
     }
     for (ChangedParameter param : changed) {
       sb.append(li_changedParam(param));
     }
     for (Parameter param : delParameters) {
-      sb.append(itemParam("** Delete ", param));
+      sb.append(itemParam("** " + I18n.getMessage("action.delete") + " ", param));
     }
     return sb.toString();
   }
 
   private String itemParam(String title, Parameter param) {
-    return title + param.getName() + " in " + param.getIn() + System.lineSeparator();
+    return title
+        + param.getName()
+        + " "
+        + I18n.getMessage("in")
+        + " "
+        + param.getIn()
+        + System.lineSeparator();
   }
 
   private String li_changedParam(ChangedParameter changeParam) {
     if (changeParam.isDeprecated()) {
-      return itemParam("** Deprecated ", changeParam.getNewParameter());
+      return itemParam(
+          "** " + I18n.getMessage("action.deprecated") + " ", changeParam.getNewParameter());
     } else {
-      return itemParam("** Changed ", changeParam.getNewParameter());
+      return itemParam(
+          "** " + I18n.getMessage("action.changed") + " ", changeParam.getNewParameter());
     }
   }
 
diff --git a/core/src/main/java/org/openapitools/openapidiff/core/output/ConsoleRender.java b/core/src/main/java/org/openapitools/openapidiff/core/output/ConsoleRender.java
index 2b8607232..8be377638 100644
--- a/core/src/main/java/org/openapitools/openapidiff/core/output/ConsoleRender.java
+++ b/core/src/main/java/org/openapitools/openapidiff/core/output/ConsoleRender.java
@@ -28,33 +28,33 @@ public class ConsoleRender implements Render {
   public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
     this.diff = diff;
     if (diff.isUnchanged()) {
-      safelyAppend(outputStreamWriter, "No differences. Specifications are equivalent");
+      safelyAppend(outputStreamWriter, I18n.getMessage("no.differences"));
     } else {
-      safelyAppend(outputStreamWriter, bigTitle("Api Change Log"));
+      safelyAppend(outputStreamWriter, bigTitle(I18n.getMessage("api.change.log")));
       safelyAppend(
           outputStreamWriter,
-          StringUtils.center(diff.getNewSpecOpenApi().getInfo().getTitle(), LINE_LENGTH));
+          centerCjk(diff.getNewSpecOpenApi().getInfo().getTitle(), LINE_LENGTH));
       safelyAppend(outputStreamWriter, System.lineSeparator());
 
       List<Endpoint> newEndpoints = diff.getNewEndpoints();
-      listEndpoints(newEndpoints, "What's New", outputStreamWriter);
+      listEndpoints(newEndpoints, I18n.getMessage("whats.new"), outputStreamWriter);
 
       List<Endpoint> missingEndpoints = diff.getMissingEndpoints();
-      listEndpoints(missingEndpoints, "What's Deleted", outputStreamWriter);
+      listEndpoints(missingEndpoints, I18n.getMessage("whats.deleted"), outputStreamWriter);
 
       List<Endpoint> deprecatedEndpoints = diff.getDeprecatedEndpoints();
-      listEndpoints(deprecatedEndpoints, "What's Deprecated", outputStreamWriter);
+      listEndpoints(deprecatedEndpoints, I18n.getMessage("whats.deprecated"), outputStreamWriter);
 
       List<ChangedOperation> changedOperations = diff.getChangedOperations();
       ol_changed(changedOperations, outputStreamWriter);
 
-      safelyAppend(outputStreamWriter, title("Result"));
+      safelyAppend(outputStreamWriter, title(I18n.getMessage("result")));
       safelyAppend(
           outputStreamWriter,
-          StringUtils.center(
+          centerCjk(
               diff.isCompatible()
-                  ? "API changes are backward compatible"
-                  : "API changes broke backward compatibility",
+                  ? I18n.getMessage("api.changes.backward.compatible")
+                  : I18n.getMessage("api.changes.broke.compatibility"),
               LINE_LENGTH));
       safelyAppend(outputStreamWriter, System.lineSeparator());
       safelyAppend(outputStreamWriter, separator('-'));
@@ -71,7 +71,7 @@ private void ol_changed(
     if (null == operations || operations.isEmpty()) {
       return;
     }
-    safelyAppend(outputStreamWriter, title("What's Changed"));
+    safelyAppend(outputStreamWriter, title(I18n.getMessage("whats.changed")));
     for (ChangedOperation operation : operations) {
       String pathUrl = operation.getPathUrl();
       String method = operation.getHttpMethod().toString();
@@ -82,25 +82,25 @@ private void ol_changed(
 
       if (result(operation.getOperationId()).isDifferent()) {
         safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
-        safelyAppend(outputStreamWriter, "Operation ID:");
+        safelyAppend(outputStreamWriter, I18n.getMessage("operation.id") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(outputStreamWriter, ul_operation_id(operation.getOperationId()));
       }
       if (result(operation.getParameters()).isDifferent()) {
         safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
-        safelyAppend(outputStreamWriter, "Parameter:");
+        safelyAppend(outputStreamWriter, I18n.getMessage("parameter") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(outputStreamWriter, ul_param(operation.getParameters()));
       }
       if (operation.resultRequestBody().isDifferent()) {
         safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
-        safelyAppend(outputStreamWriter, "Request:");
+        safelyAppend(outputStreamWriter, I18n.getMessage("request") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(outputStreamWriter, ul_content(operation.getRequestBody().getContent(), true));
       }
       if (operation.resultApiResponses().isDifferent()) {
         safelyAppend(outputStreamWriter, StringUtils.repeat(' ', 2));
-        safelyAppend(outputStreamWriter, "Return Type:");
+        safelyAppend(outputStreamWriter, I18n.getMessage("return.type") + ":");
         safelyAppend(outputStreamWriter, System.lineSeparator());
         safelyAppend(outputStreamWriter, ul_response(operation.getApiResponses()));
       }
@@ -113,13 +113,15 @@ private String ul_response(ChangedApiResponse changedApiResponse) {
     Map<String, ChangedResponse> changedResponses = changedApiResponse.getChanged();
     StringBuilder sb = new StringBuilder();
     for (String propName : addResponses.keySet()) {
-      sb.append(itemResponse("Add ", propName));
+      sb.append(itemResponse(I18n.getMessage("action.add") + " ", propName));
     }
     for (String propName : delResponses.keySet()) {
-      sb.append(itemResponse("Deleted ", propName));
+      sb.append(itemResponse(I18n.getMessage("action.deleted") + " ", propName));
     }
     for (Entry<String, ChangedResponse> entry : changedResponses.entrySet()) {
-      sb.append(itemChangedResponse("Changed ", entry.getKey(), entry.getValue()));
+      sb.append(
+          itemChangedResponse(
+              I18n.getMessage("action.changed") + " ", entry.getKey(), entry.getValue()));
     }
     return sb.toString();
   }
@@ -143,7 +145,8 @@ private String itemResponse(String title, String code) {
   private String itemChangedResponse(String title, String contentType, ChangedResponse response) {
     return itemResponse(title, contentType)
         + StringUtils.repeat(' ', 6)
-        + "Media types:"
+        + I18n.getMessage("media.types")
+        + ":"
         + System.lineSeparator()
         + ul_content(response.getContent(), false);
   }
@@ -154,14 +157,18 @@ private String ul_content(ChangedContent changedContent, boolean isRequest) {
       return sb.toString();
     }
     for (String propName : changedContent.getIncreased().keySet()) {
-      sb.append(itemContent("Added ", propName));
+      sb.append(itemContent(I18n.getMessage("action.added") + " ", propName));
     }
     for (String propName : changedContent.getMissing().keySet()) {
-      sb.append(itemContent("Deleted ", propName));
+      sb.append(itemContent(I18n.getMessage("action.deleted") + " ", propName));
     }
     for (String propName : changedContent.getChanged().keySet()) {
       sb.append(
-          itemContent("Changed ", propName, changedContent.getChanged().get(propName), isRequest));
+          itemContent(
+              I18n.getMessage("action.changed") + " ",
+              propName,
+              changedContent.getChanged().get(propName),
+              isRequest));
     }
     return sb.toString();
   }
@@ -175,8 +182,11 @@ private String itemContent(
     StringBuilder sb = new StringBuilder();
     sb.append(itemContent(title, contentType))
         .append(StringUtils.repeat(' ', 10))
-        .append("Schema: ")
-        .append(changedMediaType.isCompatible() ? "Backward compatible" : "Broken compatibility")
+        .append(I18n.getMessage("schema") + ": ")
+        .append(
+            changedMediaType.isCompatible()
+                ? I18n.getMessage("backward.compatible")
+                : I18n.getMessage("broken.compatibility"))
         .append(System.lineSeparator());
     if (!changedMediaType.isCompatible() && changedMediaType.getSchema() != null) {
       sb.append(incompatibilities(changedMediaType.getSchema()));
@@ -195,11 +205,15 @@ private String incompatibilities(String propName, final ChangedSchema schema) {
     }
     if (schema.isCoreChanged() == DiffResult.INCOMPATIBLE && schema.isChangedType()) {
       String type = type(schema.getOldSchema()) + " -> " + type(schema.getNewSchema());
-      sb.append(property(propName, "Changed property type", type));
+      sb.append(property(propName, I18n.getMessage("changed.property.type"), type));
     }
     String prefix = propName.isEmpty() ? "" : propName + ".";
     sb.append(
-        properties(prefix, "Missing property", schema.getMissingProperties(), schema.getContext()));
+        properties(
+            prefix,
+            I18n.getMessage("missing.property"),
+            schema.getMissingProperties(),
+            schema.getContext()));
     schema
         .getChangedProperties()
         .forEach((name, property) -> sb.append(incompatibilities(prefix + name, property)));
@@ -258,13 +272,13 @@ private String ul_param(ChangedParameters changedParameters) {
     List<ChangedParameter> changed = changedParameters.getChanged();
     StringBuilder sb = new StringBuilder();
     for (Parameter param : addParameters) {
-      sb.append(itemParam("Add ", param));
+      sb.append(itemParam(I18n.getMessage("action.add") + " ", param));
     }
     for (ChangedParameter param : changed) {
       sb.append(li_changedParam(param));
     }
     for (Parameter param : delParameters) {
-      sb.append(itemParam("Delete ", param));
+      sb.append(itemParam(I18n.getMessage("action.delete") + " ", param));
     }
     return sb.toString();
   }
@@ -275,16 +289,18 @@ private String itemParam(String title, Parameter param) {
         + "- "
         + title
         + param.getName()
-        + " in "
+        + " "
+        + I18n.getMessage("in")
+        + " "
         + param.getIn()
         + System.lineSeparator();
   }
 
   private String li_changedParam(ChangedParameter changeParam) {
     if (changeParam.isDeprecated()) {
-      return itemParam("Deprecated ", changeParam.getNewParameter());
+      return itemParam(I18n.getMessage("action.deprecated") + " ", changeParam.getNewParameter());
     } else {
-      return itemParam("Changed ", changeParam.getNewParameter());
+      return itemParam(I18n.getMessage("action.changed") + " ", changeParam.getNewParameter());
     }
   }
 
@@ -309,7 +325,12 @@ private String itemEndpoint(String method, String path, String desc) {
   }
 
   private String ul_operation_id(ChangedOperationId operationId) {
-    return String.format("    - Changed %s to %s\n", operationId.getLeft(), operationId.getRight());
+    return String.format(
+        "    - %s %s %s %s\n",
+        I18n.getMessage("action.changed"),
+        operationId.getLeft(),
+        I18n.getMessage("to"),
+        operationId.getRight());
   }
 
   public String renderBody(String ol_new, String ol_miss, String ol_deprec, String ol_changed) {
@@ -329,10 +350,54 @@ public String title(String title, char ch) {
     String little = StringUtils.repeat(ch, 2);
     return String.format(
         "%s%s%s%s%n%s",
-        separator(ch), little, StringUtils.center(title, LINE_LENGTH - 4), little, separator(ch));
+        separator(ch), little, centerCjk(title, LINE_LENGTH - 4), little, separator(ch));
   }
 
   public String separator(char ch) {
     return StringUtils.repeat(ch, LINE_LENGTH) + System.lineSeparator();
   }
+
+  static int displayWidth(String text) {
+    if (text == null) {
+      return 0;
+    }
+    int width = 0;
+    for (int i = 0; i < text.length(); i++) {
+      char c = text.charAt(i);
+      if (isFullWidth(c)) {
+        width += 2;
+      } else {
+        width += 1;
+      }
+    }
+    return width;
+  }
+
+  static boolean isFullWidth(char c) {
+    return (c >= '\u1100' && c <= '\u115F')
+        || (c >= '\u2E80' && c <= '\u303E')
+        || (c >= '\u3040' && c <= '\u33BF')
+        || (c >= '\u3400' && c <= '\u4DBF')
+        || (c >= '\u4E00' && c <= '\u9FFF')
+        || (c >= '\uA960' && c <= '\uA97F')
+        || (c >= '\uAC00' && c <= '\uD7FF')
+        || (c >= '\uF900' && c <= '\uFAFF')
+        || (c >= '\uFE30' && c <= '\uFE4F')
+        || (c >= '\uFF00' && c <= '\uFF60')
+        || (c >= '\uFFE0' && c <= '\uFFE6');
+  }
+
+  static String centerCjk(String text, int width) {
+    if (text == null) {
+      text = "";
+    }
+    int textWidth = displayWidth(text);
+    if (textWidth >= width) {
+      return text;
+    }
+    int totalPadding = width - textWidth;
+    int leftPadding = totalPadding / 2;
+    int rightPadding = totalPadding - leftPadding;
+    return StringUtils.repeat(' ', leftPadding) + text + StringUtils.repeat(' ', rightPadding);
+  }
 }
diff --git a/core/src/main/java/org/openapitools/openapidiff/core/output/HtmlRender.java b/core/src/main/java/org/openapitools/openapidiff/core/output/HtmlRender.java
index 441d1c9dd..6d90c2ffb 100644
--- a/core/src/main/java/org/openapitools/openapidiff/core/output/HtmlRender.java
+++ b/core/src/main/java/org/openapitools/openapidiff/core/output/HtmlRender.java
@@ -72,11 +72,15 @@ public class HtmlRender implements Render {
   protected ChangedOpenApi diff;
 
   public HtmlRender() {
-    this("Api Change Log", "http://deepoove.com/swagger-diff/stylesheets/demo.css");
+    this(
+        I18n.getMessage("api.change.log"), "http://deepoove.com/swagger-diff/stylesheets/demo.css");
   }
 
   public HtmlRender(boolean showAllChanges) {
-    this("Api Change Log", "http://deepoove.com/swagger-diff/stylesheets/demo.css", showAllChanges);
+    this(
+        I18n.getMessage("api.change.log"),
+        "http://deepoove.com/swagger-diff/stylesheets/demo.css",
+        showAllChanges);
   }
 
   public HtmlRender(String title, String linkCss) {
@@ -118,7 +122,7 @@ public void renderHtml(
       OutputStreamWriter outputStreamWriter) {
     HtmlTag html =
         html()
-            .attr("lang", "en")
+            .attr("lang", I18n.getLocale().toLanguageTag())
             .with(
                 head()
                     .with(
@@ -131,10 +135,13 @@ public void renderHtml(
                         div()
                             .withClass("article")
                             .with(
-                                div().with(h2("What's New"), hr(), ol_new),
-                                div().with(h2("What's Deleted"), hr(), ol_miss),
-                                div().with(h2("What's Deprecated"), hr(), ol_deprec),
-                                div().with(h2("What's Changed"), hr(), ol_changed))));
+                                div().with(h2(I18n.getMessage("whats.new")), hr(), ol_new),
+                                div().with(h2(I18n.getMessage("whats.deleted")), hr(), ol_miss),
+                                div()
+                                    .with(h2(I18n.getMessage("whats.deprecated")), hr(), ol_deprec),
+                                div()
+                                    .with(
+                                        h2(I18n.getMessage("whats.changed")), hr(), ol_changed))));
 
     try {
       FlatHtml<OutputStreamWriter> flatHtml = FlatHtml.into(outputStreamWriter);
@@ -205,24 +212,27 @@ private OlTag ol_changed(List<ChangedOperation> changedOperations) {
       UlTag ul_detail = ul().withClass("detail");
       if (result(changedOperation.getOperationId()).isDifferent()) {
         ul_detail.with(
-            li().with(h3("Operation ID")).with(ul_operation_id(changedOperation.getOperationId())));
+            li().with(h3(I18n.getMessage("operation.id")))
+                .with(ul_operation_id(changedOperation.getOperationId())));
       }
       if (result(changedOperation.getParameters()).isDifferent()) {
         ul_detail.with(
-            li().with(h3("Parameters")).with(ul_param(changedOperation.getParameters())));
+            li().with(h3(I18n.getMessage("parameters")))
+                .with(ul_param(changedOperation.getParameters())));
       }
       if (changedOperation.resultRequestBody().isDifferent()) {
         ul_detail.with(
-            li().with(h3("Request"))
+            li().with(h3(I18n.getMessage("request")))
                 .with(ul_request(changedOperation.getRequestBody().getContent())));
       }
       if (changedOperation.resultApiResponses().isDifferent()) {
         ul_detail.with(
-            li().with(h3("Response")).with(ul_response(changedOperation.getApiResponses())));
+            li().with(h3(I18n.getMessage("response")))
+                .with(ul_response(changedOperation.getApiResponses())));
       }
       if (showAllChanges && changedOperation.resultSecurityRequirements().isDifferent()) {
         ul_detail.with(
-            li().with(h3("Security Requirements"))
+            li().with(h3(I18n.getMessage("security.requirements")))
                 .with(ul_securityRequirements(changedOperation.getSecurityRequirements())));
       }
       ol.with(
@@ -259,18 +269,18 @@ private UlTag ul_securityRequirements(ChangedSecurityRequirements changedSecurit
   }
 
   private LiTag li_addSecurityRequirement(SecurityRequirement securityRequirement) {
-    return li().withText("New security requirement : ")
+    return li().withText(I18n.getMessage("new.security.requirement") + " ")
         .with(span(null == securityRequirement.toString() ? "" : (securityRequirement.toString())));
   }
 
   private LiTag li_missingSecurityRequirement(SecurityRequirement securityRequirement) {
-    return li().withText("Deleted security requirement : ")
+    return li().withText(I18n.getMessage("deleted.security.requirement") + " ")
         .with(span(null == securityRequirement.toString() ? "" : (securityRequirement.toString())));
   }
 
   private LiTag li_changedSecurityRequirement(
       ChangedSecurityRequirement changedSecurityRequirement) {
-    return li().withText(String.format("Changed security requirement : "))
+    return li().withText(I18n.getMessage("changed.security.requirement") + " ")
         .with(
             span(
                 (null == changedSecurityRequirement.getNewSecurityRequirement()
@@ -298,21 +308,21 @@ private UlTag ul_response(ChangedApiResponse changedApiResponse) {
   }
 
   private LiTag li_addResponse(String name, ApiResponse response) {
-    return li().withText(String.format("New response : [%s]", name))
+    return li().withText(I18n.getMessage("new.response.code", name))
         .with(
             span(null == response.getDescription() ? "" : ("//" + response.getDescription()))
                 .withClass(COMMENT));
   }
 
   private LiTag li_missingResponse(String name, ApiResponse response) {
-    return li().withText(String.format("Deleted response : [%s]", name))
+    return li().withText(I18n.getMessage("deleted.response.code", name))
         .with(
             span(null == response.getDescription() ? "" : ("//" + response.getDescription()))
                 .withClass(COMMENT));
   }
 
   private LiTag li_changedResponse(String name, ChangedResponse response) {
-    return li().withText(String.format("Changed response : [%s]", name))
+    return li().withText(I18n.getMessage("changed.response.code", name))
         .with(
             span((null == response.getNewApiResponse()
                         || null == response.getNewApiResponse().getDescription())
@@ -339,15 +349,15 @@ private UlTag ul_request(ChangedContent changedContent) {
   }
 
   private LiTag li_addRequest(String name, MediaType request) {
-    return li().withText(String.format("New body: '%s'", name));
+    return li().withText(I18n.getMessage("new.body", name));
   }
 
   private LiTag li_missingRequest(String name, MediaType request) {
-    return li().withText(String.format("Deleted body: '%s'", name));
+    return li().withText(I18n.getMessage("deleted.body", name));
   }
 
   private LiTag li_changedRequest(String name, ChangedMediaType request) {
-    LiTag li = li().withText(String.format("Changed body: '%s'", name));
+    LiTag li = li().withText(I18n.getMessage("changed.body", name));
     ChangedSchema schema = request.getSchema();
     if (schema != null) {
       li.with(div_changedSchema(schema));
@@ -362,7 +372,10 @@ private LiTag li_changedRequest(String name, ChangedMediaType request) {
 
   private DivTag div_changedSchema(ChangedSchema schema) {
     DivTag div = div();
-    div.with(h3("Schema" + (schema.isIncompatible() ? " incompatible" : "")));
+    div.with(
+        h3(
+            I18n.getMessage("schema")
+                + (schema.isIncompatible() ? " " + I18n.getMessage("schema.incompatible") : "")));
     return div;
   }
 
@@ -374,12 +387,24 @@ private void allChanges(
       final ContainerTag<?> output, String propName, final ChangedSchema schema) {
     String prefix = propName.isEmpty() ? "" : propName + ".";
     properties(
-        output, prefix, "Missing property", schema.getMissingProperties(), schema.getContext());
+        output,
+        prefix,
+        I18n.getMessage("missing.property"),
+        schema.getMissingProperties(),
+        schema.getContext());
     properties(
-        output, prefix, "Added property", schema.getIncreasedProperties(), schema.getContext());
+        output,
+        prefix,
+        I18n.getMessage("added.property"),
+        schema.getIncreasedProperties(),
+        schema.getContext());
 
     propertiesChanged(
-        output, prefix, "Changed property", schema.getChangedProperties(), schema.getContext());
+        output,
+        prefix,
+        I18n.getMessage("changed.property"),
+        schema.getChangedProperties(),
+        schema.getContext());
     if (schema.getItems() != null) {
       itemsAllChanges(output, propName, schema.getItems());
     }
@@ -399,11 +424,15 @@ private void incompatibilities(
     }
     if (schema.isCoreChanged() == DiffResult.INCOMPATIBLE && schema.isChangedType()) {
       String type = type(schema.getOldSchema()) + " -> " + type(schema.getNewSchema());
-      property(output, propName, "Changed property type", type);
+      property(output, propName, I18n.getMessage("changed.property.type"), type);
     }
     String prefix = propName.isEmpty() ? "" : propName + ".";
     properties(
-        output, prefix, "Missing property", schema.getMissingProperties(), schema.getContext());
+        output,
+        prefix,
+        I18n.getMessage("missing.property"),
+        schema.getMissingProperties(),
+        schema.getContext());
     schema
         .getChangedProperties()
         .forEach((name, property) -> incompatibilities(output, prefix + name, property));
@@ -511,7 +540,14 @@ private UlTag ul_param(ChangedParameters changedParameters) {
   }
 
   private LiTag li_addParam(Parameter param) {
-    return li().withText("Add " + param.getName() + " in " + param.getIn())
+    return li().withText(
+            I18n.getMessage("action.add")
+                + " "
+                + param.getName()
+                + " "
+                + I18n.getMessage("in")
+                + " "
+                + param.getIn())
         .with(
             span(null == param.getDescription() ? "" : ("//" + param.getDescription()))
                 .withClass(COMMENT));
@@ -519,9 +555,9 @@ private LiTag li_addParam(Parameter param) {
 
   private LiTag li_missingParam(Parameter param) {
     return li().withClass(MISSING)
-        .with(span("Delete"))
+        .with(span(I18n.getMessage("action.delete")))
         .with(del(param.getName()))
-        .with(span("in ").withText(param.getIn()))
+        .with(span(I18n.getMessage("in") + " ").withText(param.getIn()))
         .with(
             span(null == param.getDescription() ? "" : ("//" + param.getDescription()))
                 .withClass(COMMENT));
@@ -529,9 +565,9 @@ private LiTag li_missingParam(Parameter param) {
 
   private LiTag li_deprecatedParam(ChangedParameter param) {
     return li().withClass(MISSING)
-        .with(span("Deprecated"))
+        .with(span(I18n.getMessage("action.deprecated")))
         .with(del(param.getName()))
-        .with(span("in ").withText(param.getIn()))
+        .with(span(I18n.getMessage("in") + " ").withText(param.getIn()))
         .with(
             span(null == param.getNewParameter().getDescription()
                     ? ""
@@ -550,18 +586,22 @@ private LiTag li_changedParam(ChangedParameter changeParam) {
             .orElse(false);
     Parameter rightParam = changeParam.getNewParameter();
     Parameter leftParam = changeParam.getOldParameter();
-    LiTag li = li().withText(changeParam.getName() + " in " + changeParam.getIn());
+    LiTag li =
+        li().withText(
+                changeParam.getName() + " " + I18n.getMessage("in") + " " + changeParam.getIn());
     if (changeRequired) {
       li.withText(
-          " change into "
+          " "
+              + I18n.getMessage("change.into")
+              + " "
               + (rightParam.getRequired() != null && rightParam.getRequired()
-                  ? "required"
-                  : "not required"));
+                  ? I18n.getMessage("required")
+                  : I18n.getMessage("not.required")));
     }
     if (changeDescription) {
-      li.withText(" Notes ")
+      li.withText(" " + I18n.getMessage("notes") + " ")
           .with(del(leftParam.getDescription()).withClass(COMMENT))
-          .withText(" change into ")
+          .withText(" " + I18n.getMessage("change.into") + " ")
           .with(span(rightParam.getDescription()).withClass(COMMENT));
     }
     return li;
@@ -571,9 +611,12 @@ private UlTag ul_operation_id(ChangedOperationId changedOperationId) {
     return ul().withClass("change")
         .with(
             li().withText(
-                    "Changed "
+                    I18n.getMessage("action.changed")
+                        + " "
                         + Optional.ofNullable(changedOperationId.getLeft()).orElse("")
-                        + " to "
+                        + " "
+                        + I18n.getMessage("to")
+                        + " "
                         + Optional.ofNullable(changedOperationId.getRight()).orElse("")));
   }
 }
diff --git a/core/src/main/java/org/openapitools/openapidiff/core/output/I18n.java b/core/src/main/java/org/openapitools/openapidiff/core/output/I18n.java
new file mode 100644
index 000000000..342c4dc2c
--- /dev/null
+++ b/core/src/main/java/org/openapitools/openapidiff/core/output/I18n.java
@@ -0,0 +1,72 @@
+package org.openapitools.openapidiff.core.output;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.Locale;
+import java.util.PropertyResourceBundle;
+import java.util.ResourceBundle;
+
+public final class I18n {
+
+  private static final String BUNDLE_NAME = "i18n.messages";
+  private static volatile Locale currentLocale = Locale.ENGLISH;
+  private static volatile ResourceBundle bundle = loadBundle(currentLocale);
+
+  private I18n() {}
+
+  public static synchronized void setLocale(Locale locale) {
+    bundle = loadBundle(locale);
+    currentLocale = locale;
+  }
+
+  public static Locale getLocale() {
+    return currentLocale;
+  }
+
+  public static String getMessage(String key) {
+    return bundle.getString(key);
+  }
+
+  public static String getMessage(String key, Object... args) {
+    return String.format(bundle.getString(key), args);
+  }
+
+  public static Locale parseLocale(String lang) {
+    switch (lang.toLowerCase().replace("_", "-")) {
+      case "zh-hant":
+      case "zh-tw":
+        return Locale.TRADITIONAL_CHINESE;
+      case "zh-hans":
+      case "zh-cn":
+        return Locale.SIMPLIFIED_CHINESE;
+      case "en":
+      default:
+        return Locale.ENGLISH;
+    }
+  }
+
+  private static ResourceBundle loadBundle(Locale locale) {
+    return ResourceBundle.getBundle(BUNDLE_NAME, locale, new UTF8Control());
+  }
+
+  private static class UTF8Control extends ResourceBundle.Control {
+    @Override
+    public ResourceBundle newBundle(
+        String baseName, Locale locale, String format, ClassLoader loader, boolean reload)
+        throws IllegalAccessException, InstantiationException, IOException {
+      String bundleName = toBundleName(baseName, locale);
+      String resourceName = toResourceName(bundleName, "properties");
+      InputStream stream = loader.getResourceAsStream(resourceName);
+      if (stream != null) {
+        try {
+          return new PropertyResourceBundle(new InputStreamReader(stream, StandardCharsets.UTF_8));
+        } finally {
+          stream.close();
+        }
+      }
+      return super.newBundle(baseName, locale, format, loader, reload);
+    }
+  }
+}
diff --git a/core/src/main/java/org/openapitools/openapidiff/core/output/MarkdownRender.java b/core/src/main/java/org/openapitools/openapidiff/core/output/MarkdownRender.java
index 531fd3809..a64d3725c 100644
--- a/core/src/main/java/org/openapitools/openapidiff/core/output/MarkdownRender.java
+++ b/core/src/main/java/org/openapitools/openapidiff/core/output/MarkdownRender.java
@@ -57,11 +57,12 @@ public void render(ChangedOpenApi diff, OutputStreamWriter outputStreamWriter) {
         diff.getNewSpecOpenApi().getInfo().getTitle(),
         diff.getNewSpecOpenApi().getInfo().getVersion(),
         outputStreamWriter);
-    listEndpoints("What's New", diff.getNewEndpoints(), outputStreamWriter);
-    listEndpoints("What's Deleted", diff.getMissingEndpoints(), outputStreamWriter);
-    listEndpoints("What's Deprecated", diff.getDeprecatedEndpoints(), outputStreamWriter);
+    listEndpoints(I18n.getMessage("whats.new"), diff.getNewEndpoints(), outputStreamWriter);
+    listEndpoints(I18n.getMessage("whats.deleted"), diff.getMissingEndpoints(), outputStreamWriter);
+    listEndpoints(
+        I18n.getMessage("whats.deprecated"), diff.getDeprecatedEndpoints(), outputStreamWriter);
     listEndpoints(diff.getChangedOperations(), outputStreamWriter);
-    changeSummary("Result", diff, outputStreamWriter);
+    changeSummary(I18n.getMessage("result"), diff, outputStreamWriter);
     try {
       outputStreamWriter.close();
     } catch (IOException e) {
@@ -82,11 +83,11 @@ protected void changeSummary(
     safelyAppend(outputStreamWriter, sectionTitle(title));
 
     if (diff.isUnchanged()) {
-      safelyAppend(outputStreamWriter, "No differences. Specifications are equivalent");
+      safelyAppend(outputStreamWriter, I18n.getMessage("no.differences"));
     } else if (diff.isCompatible()) {
-      safelyAppend(outputStreamWriter, "API changes are backward compatible");
+      safelyAppend(outputStreamWriter, I18n.getMessage("api.changes.backward.compatible"));
     } else {
-      safelyAppend(outputStreamWriter, "API changes broke backward compatibility");
+      safelyAppend(outputStreamWriter, I18n.getMessage("api.changes.broke.compatibility"));
     }
 
     safelyAppend(outputStreamWriter, "\n\n");
@@ -124,7 +125,7 @@ protected void listEndpoints(
     if (null == changedOperations || changedOperations.isEmpty()) {
       return;
     }
-    safelyAppend(outputStreamWriter, sectionTitle("What's Changed"));
+    safelyAppend(outputStreamWriter, sectionTitle(I18n.getMessage("whats.changed")));
     changedOperations.forEach(
         operation -> {
           safelyAppend(
@@ -134,22 +135,23 @@ protected void listEndpoints(
                   operation.getPathUrl(),
                   operation.getSummary()));
           if (result(operation.getOperationId()).isDifferent()) {
-            safelyAppend(outputStreamWriter, titleH5("Operation ID:"));
+            safelyAppend(outputStreamWriter, titleH5(I18n.getMessage("operation.id") + ":"));
             safelyAppend(outputStreamWriter, operationId(operation.getOperationId()));
           }
           if (result(operation.getParameters()).isDifferent()) {
-            safelyAppend(outputStreamWriter, titleH5("Parameters:"));
+            safelyAppend(outputStreamWriter, titleH5(I18n.getMessage("parameters") + ":"));
             safelyAppend(outputStreamWriter, parameters(operation.getParameters()));
           }
           if (operation.resultRequestBody().isDifferent()) {
-            safelyAppend(outputStreamWriter, titleH5("Request:"));
+            safelyAppend(outputStreamWriter, titleH5(I18n.getMessage("request") + ":"));
             safelyAppend(
                 outputStreamWriter,
-                metadata("Description", operation.getRequestBody().getDescription()));
+                metadata(
+                    I18n.getMessage("description"), operation.getRequestBody().getDescription()));
             safelyAppend(outputStreamWriter, bodyContent(operation.getRequestBody().getContent()));
           }
           if (operation.resultApiResponses().isDifferent()) {
-            safelyAppend(outputStreamWriter, titleH5("Return Type:"));
+            safelyAppend(outputStreamWriter, titleH5(I18n.getMessage("return.type") + ":"));
             safelyAppend(outputStreamWriter, responses(operation.getApiResponses()));
           }
         });
@@ -157,8 +159,8 @@ protected void listEndpoints(
 
   protected String responses(ChangedApiResponse changedApiResponse) {
     StringBuilder sb = new StringBuilder("\n");
-    sb.append(listResponse("New response", changedApiResponse.getIncreased()));
-    sb.append(listResponse("Deleted response", changedApiResponse.getMissing()));
+    sb.append(listResponse(I18n.getMessage("new.response"), changedApiResponse.getIncreased()));
+    sb.append(listResponse(I18n.getMessage("deleted.response"), changedApiResponse.getMissing()));
     changedApiResponse.getChanged().entrySet().stream()
         .map(e -> this.itemResponse(e.getKey(), e.getValue()))
         .forEach(sb::append);
@@ -181,7 +183,7 @@ protected String itemResponse(String code, ChangedResponse response) {
     StringBuilder sb = new StringBuilder();
     sb.append(
         this.itemResponse(
-            "Changed response",
+            I18n.getMessage("changed.response"),
             code,
             null == response.getNewApiResponse()
                 ? ""
@@ -207,8 +209,8 @@ protected String itemResponse(String title, String code, String description) {
   protected String headers(ChangedHeaders headers) {
     StringBuilder sb = new StringBuilder();
     if (headers != null) {
-      sb.append(listHeader("New header", headers.getIncreased()))
-          .append(listHeader("Deleted header", headers.getMissing()));
+      sb.append(listHeader(I18n.getMessage("new.header"), headers.getIncreased()))
+          .append(listHeader(I18n.getMessage("deleted.header"), headers.getMissing()));
       headers.getChanged().entrySet().stream()
           .map(e -> this.itemHeader(e.getKey(), e.getValue()))
           .forEach(sb::append);
@@ -230,7 +232,7 @@ protected String itemHeader(String title, String name, Header header) {
 
   protected String itemHeader(String code, ChangedHeader header) {
     return this.itemHeader(
-        "Changed header",
+        I18n.getMessage("changed.header"),
         code,
         null == header.getNewHeader() ? "" : header.getNewHeader().getDescription());
   }
@@ -244,8 +246,10 @@ protected String bodyContent(String prefix, ChangedContent changedContent) {
       return "";
     }
     StringBuilder sb = new StringBuilder("\n");
-    sb.append(listContent(prefix, "New content type", changedContent.getIncreased()));
-    sb.append(listContent(prefix, "Deleted content type", changedContent.getMissing()));
+    sb.append(
+        listContent(prefix, I18n.getMessage("new.content.type"), changedContent.getIncreased()));
+    sb.append(
+        listContent(prefix, I18n.getMessage("deleted.content.type"), changedContent.getMissing()));
     final int deepness;
     if (StringUtils.isNotBlank(prefix)) {
       deepness = 1;
@@ -279,7 +283,7 @@ protected String itemContent(String title, String mediaType, MediaType content)
   }
 
   protected String itemContent(int deepness, String mediaType, ChangedMediaType content) {
-    String result = itemContent("Changed content type", mediaType);
+    String result = itemContent(I18n.getMessage("changed.content.type"), mediaType);
     if (content.getSchema() != null) {
       result += schema(deepness, content.getSchema());
     }
@@ -296,18 +300,31 @@ protected String oneOfSchema(int deepness, ChangedOneOfSchema schema, String dis
         .getMissing()
         .keySet()
         .forEach(
-            key -> sb.append(format("%sDeleted '%s' %s\n", indent(deepness), key, discriminator)));
+            key ->
+                sb.append(
+                    format(
+                        "%s%s '%s' %s\n",
+                        indent(deepness), I18n.getMessage("action.deleted"), key, discriminator)));
     schema
         .getIncreased()
         .forEach(
             (key, sub) ->
-                sb.append(format("%sAdded '%s' %s:\n", indent(deepness), key, discriminator))
+                sb.append(
+                        format(
+                            "%s%s '%s' %s:\n",
+                            indent(deepness), I18n.getMessage("action.added"), key, discriminator))
                     .append(schema(deepness, sub, schema.getContext())));
     schema
         .getChanged()
         .forEach(
             (key, sub) ->
-                sb.append(format("%sUpdated `%s` %s:\n", indent(deepness), key, discriminator))
+                sb.append(
+                        format(
+                            "%s%s `%s` %s:\n",
+                            indent(deepness),
+                            I18n.getMessage("action.updated"),
+                            key,
+                            discriminator))
                     .append(schema(deepness, sub)));
     return sb.toString();
   }
@@ -335,24 +352,32 @@ protected String schema(int deepness, ChangedSchema schema) {
       sb.append(oneOfSchema(deepness, schema.getOneOfSchema(), discriminator));
     }
     if (schema.getRequired() != null) {
-      sb.append(required(deepness, "New required properties", schema.getRequired().getIncreased()));
-      sb.append(required(deepness, "New optional properties", schema.getRequired().getMissing()));
+      sb.append(
+          required(
+              deepness,
+              I18n.getMessage("new.required.properties"),
+              schema.getRequired().getIncreased()));
+      sb.append(
+          required(
+              deepness,
+              I18n.getMessage("new.optional.properties"),
+              schema.getRequired().getMissing()));
     }
     if (schema.getItems() != null) {
       sb.append(items(deepness, schema.getItems()));
     }
-    sb.append(listDiff(deepness, "enum", schema.getEnumeration()));
+    sb.append(listDiff(deepness, I18n.getMessage("enum"), schema.getEnumeration()));
     sb.append(
         properties(
             deepness,
-            "Added property",
+            I18n.getMessage("added.property"),
             schema.getIncreasedProperties(),
             true,
             schema.getContext()));
     sb.append(
         properties(
             deepness,
-            "Deleted property",
+            I18n.getMessage("deleted.property"),
             schema.getMissingProperties(),
             false,
             schema.getContext()));
@@ -372,7 +397,7 @@ protected String schema(int deepness, ComposedSchema schema, DiffContext context
     }
     if (schema.getOneOf() != null) {
       LOGGER.debug("One of schema");
-      sb.append(format("%sOne of:\n\n", indent(deepness)));
+      sb.append(format("%s%s:\n\n", indent(deepness), I18n.getMessage("one.of")));
       schema.getOneOf().stream()
           .map(this::resolve)
           .forEach(composedChild -> sb.append(schema(deepness + 1, composedChild, context)));
@@ -384,8 +409,9 @@ protected String schema(int deepness, Schema schema, DiffContext context) {
     if (handledSchemas.contains(schema)) return "";
     handledSchemas.add(schema);
     StringBuilder sb = new StringBuilder();
-    sb.append(listItem(deepness, "Enum", schema.getEnum()));
-    sb.append(properties(deepness, "Property", schema.getProperties(), true, context));
+    sb.append(listItem(deepness, I18n.getMessage("enum.label"), schema.getEnum()));
+    sb.append(
+        properties(deepness, I18n.getMessage("property"), schema.getProperties(), true, context));
     if (schema instanceof ComposedSchema) {
       sb.append(schema(deepness, (ComposedSchema) schema, context));
     } else if (schema instanceof ArraySchema) {
@@ -400,13 +426,18 @@ protected String items(int deepness, ChangedSchema schema) {
     if (schema.isChangedType()) {
       type = type(schema.getOldSchema()) + " -> " + type(schema.getNewSchema());
     }
-    sb.append(items(deepness, "Changed items", type, schema.getNewSchema().getDescription()));
+    sb.append(
+        items(
+            deepness,
+            I18n.getMessage("changed.items"),
+            type,
+            schema.getNewSchema().getDescription()));
     sb.append(schema(deepness, schema));
     return sb.toString();
   }
 
   protected String items(int deepness, Schema<?> schema, DiffContext context) {
-    return items(deepness, "Items", type(schema), schema.getDescription())
+    return items(deepness, I18n.getMessage("items"), type(schema), schema.getDescription())
         + schema(deepness, schema, context);
   }
 
@@ -450,7 +481,12 @@ protected String property(int deepness, String name, ChangedSchema schema) {
       type = type(schema.getOldSchema()) + " -> " + type(schema.getNewSchema());
     }
     sb.append(
-        property(deepness, "Changed property", name, type, schema.getNewSchema().getDescription()));
+        property(
+            deepness,
+            I18n.getMessage("changed.property"),
+            name,
+            type,
+            schema.getNewSchema().getDescription()));
     sb.append(schema(++deepness, schema));
     return sb.toString();
   }
@@ -470,14 +506,16 @@ protected String listDiff(int deepness, String name, ChangedList<?> listDiff) {
     if (listDiff == null) {
       return "";
     }
-    return listItem(deepness, "Added " + name, listDiff.getIncreased())
-        + listItem(deepness, "Removed " + name, listDiff.getMissing());
+    return listItem(deepness, I18n.getMessage("action.added") + " " + name, listDiff.getIncreased())
+        + listItem(deepness, I18n.getMessage("action.removed") + " " + name, listDiff.getMissing());
   }
 
   protected <T> String listItem(int deepness, String name, List<T> list) {
     StringBuilder sb = new StringBuilder();
     if (list != null && !list.isEmpty()) {
-      sb.append(format("%s%s value%s:\n\n", indent(deepness), name, list.size() > 1 ? "s" : ""));
+      String valueWord =
+          list.size() > 1 ? I18n.getMessage("value.plural") : I18n.getMessage("value.singular");
+      sb.append(format("%s%s %s:\n\n", indent(deepness), name, valueWord));
       list.forEach(p -> sb.append(format("%s* `%s`\n", indent(deepness), p)));
     }
     return sb.toString();
@@ -486,8 +524,8 @@ protected <T> String listItem(int deepness, String name, List<T> list) {
   protected String parameters(ChangedParameters changedParameters) {
     List<ChangedParameter> changed = changedParameters.getChanged();
     StringBuilder sb = new StringBuilder("\n");
-    sb.append(listParameter("Added", changedParameters.getIncreased()))
-        .append(listParameter("Deleted", changedParameters.getMissing()));
+    sb.append(listParameter(I18n.getMessage("action.added"), changedParameters.getIncreased()))
+        .append(listParameter(I18n.getMessage("action.deleted"), changedParameters.getMissing()));
     changed.stream().map(this::itemParameter).forEach(sb::append);
     return sb.toString();
   }
@@ -506,7 +544,9 @@ protected String itemParameter(String title, Parameter parameter) {
   protected String itemParameter(String title, String name, String in, String description) {
     return format("%s: ", title)
         + code(name)
-        + " in "
+        + " "
+        + I18n.getMessage("in")
+        + " "
         + code(in)
         + '\n'
         + metadata(description)
@@ -517,10 +557,16 @@ protected String itemParameter(ChangedParameter param) {
     Parameter rightParam = param.getNewParameter();
     if (param.isDeprecated()) {
       return itemParameter(
-          "Deprecated", rightParam.getName(), rightParam.getIn(), rightParam.getDescription());
+          I18n.getMessage("action.deprecated"),
+          rightParam.getName(),
+          rightParam.getIn(),
+          rightParam.getDescription());
     }
     return itemParameter(
-        "Changed", rightParam.getName(), rightParam.getIn(), rightParam.getDescription());
+        I18n.getMessage("action.changed"),
+        rightParam.getName(),
+        rightParam.getIn(),
+        rightParam.getDescription());
   }
 
   protected String code(String string) {
@@ -537,9 +583,11 @@ protected String metadata(String beginning, String name, ChangedMetadata changed
     }
     if (!isUnchanged(changedMetadata) && showChangedMetadata) {
       return format(
-          "Changed %s:\n%s\nto:\n%s\n\n",
+          "%s %s:\n%s\n%s:\n%s\n\n",
+          I18n.getMessage("action.changed"),
           name,
           metadata(beginning, changedMetadata.getLeft()),
+          I18n.getMessage("to"),
           metadata(beginning, changedMetadata.getRight()));
     } else {
       return metadata(beginning, name, changedMetadata.getRight());
@@ -548,7 +596,11 @@ protected String metadata(String beginning, String name, ChangedMetadata changed
 
   protected String operationId(ChangedOperationId operationId) {
     return String.format(
-        "\nChanged: %s to %s\n\n", code(operationId.getLeft()), code(operationId.getRight()));
+        "\n%s: %s %s %s\n\n",
+        I18n.getMessage("action.changed"),
+        code(operationId.getLeft()),
+        I18n.getMessage("to"),
+        code(operationId.getRight()));
   }
 
   protected String metadata(String metadata) {
diff --git a/core/src/main/resources/i18n/messages.properties b/core/src/main/resources/i18n/messages.properties
new file mode 100644
index 000000000..713c36ad5
--- /dev/null
+++ b/core/src/main/resources/i18n/messages.properties
@@ -0,0 +1,107 @@
+# Section Headers
+whats.new=What's New
+whats.deleted=What's Deleted
+whats.deprecated=What's Deprecated
+whats.changed=What's Changed
+result=Result
+
+# Page Titles
+api.change.log=Api Change Log
+
+# Labels
+operation.id=Operation ID
+parameter=Parameter
+parameters=Parameters
+request=Request
+return.type=Return Type
+response=Response
+schema=Schema
+media.types=Media types
+security.requirements=Security Requirements
+description=Description
+
+# Actions
+action.add=Add
+action.added=Added
+action.delete=Delete
+action.deleted=Deleted
+action.changed=Changed
+action.deprecated=Deprecated
+action.updated=Updated
+action.removed=Removed
+
+# Property Labels
+added.property=Added property
+deleted.property=Deleted property
+changed.property=Changed property
+changed.property.type=Changed property type
+missing.property=Missing property
+property=Property
+
+# Content Type
+new.content.type=New content type
+deleted.content.type=Deleted content type
+changed.content.type=Changed content type
+
+# Body
+new.body=New body: '%s'
+deleted.body=Deleted body: '%s'
+changed.body=Changed body: '%s'
+
+# Response
+new.response=New response
+deleted.response=Deleted response
+changed.response=Changed response
+new.response.code=New response : [%s]
+deleted.response.code=Deleted response : [%s]
+changed.response.code=Changed response : [%s]
+
+# Header
+new.header=New header
+deleted.header=Deleted header
+changed.header=Changed header
+
+# Security
+new.security.requirement=New security requirement :
+deleted.security.requirement=Deleted security requirement :
+changed.security.requirement=Changed security requirement :
+
+# Schema
+backward.compatible=Backward compatible
+broken.compatibility=Broken compatibility
+schema.incompatible=incompatible
+new.required.properties=New required properties
+new.optional.properties=New optional properties
+items=Items
+changed.items=Changed items
+enum=enum
+enum.label=Enum
+one.of=One of
+
+# Compatibility Messages
+api.changes.backward.compatible=API changes are backward compatible
+api.changes.broke.compatibility=API changes broke backward compatibility
+no.differences=No differences. Specifications are equivalent
+
+# Asciidoc specific
+note.no.differences=NOTE: No differences. Specifications are equivalent
+note.backward.compatible=NOTE: API changes are backward compatible
+warning.broke.compatibility=WARNING: API changes broke backward compatibility
+
+# Misc
+in=in
+to=to
+change.into=change into
+required=required
+not.required=not required
+notes=Notes
+value.singular=value
+value.plural=values
+
+# CLI
+cli.version.prefix=openapi-diff version:
+cli.parsing.failed=Parsing failed. Reason:
+cli.unexpected.exception=Unexpected exception. Reason:
+cli.missing.arguments=Missing arguments
+cli.invalid.log.level=Invalid log level. Expected: [TRACE, DEBUG, INFO, WARN, ERROR, OFF]. Given: %s
+cli.config.prop.unexpected.format=--config-prop unexpected format:
diff --git a/core/src/main/resources/i18n/messages_zh_CN.properties b/core/src/main/resources/i18n/messages_zh_CN.properties
new file mode 100644
index 000000000..bea5a22d8
--- /dev/null
+++ b/core/src/main/resources/i18n/messages_zh_CN.properties
@@ -0,0 +1,107 @@
+# 章节标题
+whats.new=新增项目
+whats.deleted=删除项目
+whats.deprecated=弃用项目
+whats.changed=变更项目
+result=结果
+
+# 页面标题
+api.change.log=API 变更日志
+
+# 标签
+operation.id=操作 ID
+parameter=参数
+parameters=参数
+request=请求
+return.type=响应类型
+response=响应
+schema=结构描述
+media.types=媒体类型
+security.requirements=安全性需求
+description=描述
+
+# 操作
+action.add=新增
+action.added=新增
+action.delete=删除
+action.deleted=已删除
+action.changed=变更
+action.deprecated=已弃用
+action.updated=已更新
+action.removed=移除
+
+# 属性标签
+added.property=新增属性
+deleted.property=删除属性
+changed.property=变更属性
+changed.property.type=变更属性类型
+missing.property=缺少属性
+property=属性
+
+# 内容类型
+new.content.type=新增内容类型
+deleted.content.type=删除内容类型
+changed.content.type=变更内容类型
+
+# 主体
+new.body=新增主体：'%s'
+deleted.body=删除主体：'%s'
+changed.body=变更主体：'%s'
+
+# 响应
+new.response=新增响应
+deleted.response=删除响应
+changed.response=变更响应
+new.response.code=新增响应：[%s]
+deleted.response.code=删除响应：[%s]
+changed.response.code=变更响应：[%s]
+
+# 标头
+new.header=新增标头
+deleted.header=删除标头
+changed.header=变更标头
+
+# 安全性
+new.security.requirement=新增安全性需求：
+deleted.security.requirement=删除安全性需求：
+changed.security.requirement=变更安全性需求：
+
+# 结构描述
+backward.compatible=向后兼容
+broken.compatibility=兼容性中断
+schema.incompatible=不兼容
+new.required.properties=新增必要属性
+new.optional.properties=新增可选属性
+items=项目
+changed.items=变更项目
+enum=枚举
+enum.label=枚举
+one.of=其中之一
+
+# 兼容性消息
+api.changes.backward.compatible=API 变更具向后兼容性
+api.changes.broke.compatibility=API 变更破坏了向后兼容性
+no.differences=无差异，规格相同
+
+# Asciidoc 专用
+note.no.differences=NOTE: 无差异，规格相同
+note.backward.compatible=NOTE: API 变更具向后兼容性
+warning.broke.compatibility=WARNING: API 变更破坏了向后兼容性
+
+# 其他
+in=于
+to=为
+change.into=变更为
+required=必要
+not.required=非必要
+notes=备注
+value.singular=值
+value.plural=值
+
+# CLI
+cli.version.prefix=openapi-diff 版本：
+cli.parsing.failed=解析失败。原因：
+cli.unexpected.exception=发生非预期的异常。原因：
+cli.missing.arguments=缺少参数
+cli.invalid.log.level=无效的日志等级。预期：[TRACE, DEBUG, INFO, WARN, ERROR, OFF]。输入：%s
+cli.config.prop.unexpected.format=--config-prop 格式不正确：
diff --git a/core/src/main/resources/i18n/messages_zh_TW.properties b/core/src/main/resources/i18n/messages_zh_TW.properties
new file mode 100644
index 000000000..d2541a0c7
--- /dev/null
+++ b/core/src/main/resources/i18n/messages_zh_TW.properties
@@ -0,0 +1,107 @@
+# 章節標題
+whats.new=新增項目
+whats.deleted=刪除項目
+whats.deprecated=棄用項目
+whats.changed=變更項目
+result=結果
+
+# 頁面標題
+api.change.log=API 變更日誌
+
+# 標籤
+operation.id=操作 ID
+parameter=參數
+parameters=參數
+request=請求
+return.type=回應類型
+response=回應
+schema=結構描述
+media.types=媒體類型
+security.requirements=安全性需求
+description=描述
+
+# 操作
+action.add=新增
+action.added=新增
+action.delete=刪除
+action.deleted=已刪除
+action.changed=變更
+action.deprecated=已棄用
+action.updated=已更新
+action.removed=移除
+
+# 屬性標籤
+added.property=新增屬性
+deleted.property=刪除屬性
+changed.property=變更屬性
+changed.property.type=變更屬性類型
+missing.property=缺少屬性
+property=屬性
+
+# 內容類型
+new.content.type=新增內容類型
+deleted.content.type=刪除內容類型
+changed.content.type=變更內容類型
+
+# 主體
+new.body=新增主體：'%s'
+deleted.body=刪除主體：'%s'
+changed.body=變更主體：'%s'
+
+# 回應
+new.response=新增回應
+deleted.response=刪除回應
+changed.response=變更回應
+new.response.code=新增回應：[%s]
+deleted.response.code=刪除回應：[%s]
+changed.response.code=變更回應：[%s]
+
+# 標頭
+new.header=新增標頭
+deleted.header=刪除標頭
+changed.header=變更標頭
+
+# 安全性
+new.security.requirement=新增安全性需求：
+deleted.security.requirement=刪除安全性需求：
+changed.security.requirement=變更安全性需求：
+
+# 結構描述
+backward.compatible=向後相容
+broken.compatibility=相容性中斷
+schema.incompatible=不相容
+new.required.properties=新增必要屬性
+new.optional.properties=新增選用屬性
+items=項目
+changed.items=變更項目
+enum=列舉
+enum.label=列舉
+one.of=其中之一
+
+# 相容性訊息
+api.changes.backward.compatible=API 變更具向後相容性
+api.changes.broke.compatibility=API 變更破壞了向後相容性
+no.differences=無差異，規格相同
+
+# Asciidoc 專用
+note.no.differences=NOTE: 無差異，規格相同
+note.backward.compatible=NOTE: API 變更具向後相容性
+warning.broke.compatibility=WARNING: API 變更破壞了向後相容性
+
+# 其他
+in=於
+to=為
+change.into=變更為
+required=必要
+not.required=非必要
+notes=備註
+value.singular=值
+value.plural=值
+
+# CLI
+cli.version.prefix=openapi-diff 版本：
+cli.parsing.failed=解析失敗。原因：
+cli.unexpected.exception=發生非預期的例外。原因：
+cli.missing.arguments=缺少參數
+cli.invalid.log.level=無效的日誌等級。預期：[TRACE, DEBUG, INFO, WARN, ERROR, OFF]。輸入：%s
+cli.config.prop.unexpected.format=--config-prop 格式不正確：