diff --git a/eslint.config.js b/eslint.config.js
index 86dd5831..450038a5 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -102,6 +102,12 @@ export default [
       '@typescript-eslint/explicit-module-boundary-types': 'off',
       '@typescript-eslint/naming-convention': [
         'error',
+        {
+          selector: 'typeLike',
+          format: ['PascalCase'],
+          leadingUnderscore: 'forbid',
+          trailingUnderscore: 'forbid',
+        },
         {
           selector: 'accessor',
           format: ['camelCase', 'PascalCase'],
@@ -127,12 +133,6 @@ export default [
           leadingUnderscore: 'forbid',
           trailingUnderscore: 'forbid',
         },
-        {
-          selector: 'interface',
-          format: ['PascalCase'],
-          leadingUnderscore: 'forbid',
-          trailingUnderscore: 'forbid',
-        },
         {
           selector: 'variable',
           format: ['camelCase', 'UPPER_CASE'],
diff --git a/src/script/Background.ts b/src/script/Background.ts
index 66026a7e..a8816844 100644
--- a/src/script/Background.ts
+++ b/src/script/Background.ts
@@ -5,6 +5,47 @@ import Translation from '@APF/Translation';
 import WebConfig from '@APF/WebConfig';
 import { formatNumber } from '@APF/lib/helper';
 import Logger from '@APF/lib/Logger';
+import type { Summary } from '@APF/WebFilter';
+
+export interface BackgroundData {
+  disabledTab?: boolean;
+}
+
+export interface BackgroundStorage {
+  tabs?: {
+    [tabId: number]: TabStorageOptions;
+  };
+}
+
+export interface Message {
+  advanced?: boolean;
+  backgroundData?: boolean;
+  counter?: number;
+  deep?: boolean;
+  destination: string;
+  disabled?: boolean;
+  enableTab?: boolean;
+  forceUpdate?: boolean;
+  getStatus?: boolean;
+  globalVariable?: string;
+  iframe?: boolean;
+  popup?: boolean;
+  source: string;
+  status?: number;
+  summary?: Summary;
+  tabId?: number;
+  updateContextMenus?: boolean;
+  urlUpdate?: string;
+}
+
+export interface TabStorageOptions {
+  counters?: { number?: number };
+  disabled?: boolean;
+  disabledOnce?: number; // NOT_SET: 0, DISABLED: 1, WILL_DISABLE: 2
+  id?: number;
+  registeredAt?: number;
+  status?: number;
+}
 
 export default class Background {
   //#region Class reference helpers
diff --git a/src/script/BookmarkletFilter.ts b/src/script/BookmarkletFilter.ts
index c9196cd0..a1057e29 100644
--- a/src/script/BookmarkletFilter.ts
+++ b/src/script/BookmarkletFilter.ts
@@ -4,6 +4,8 @@ import Domain from '@APF/Domain';
 import Filter from '@APF/lib/Filter';
 import Page from '@APF/Page';
 import WebConfig from '@APF/WebConfig';
+import type { BackgroundData, Message } from '@APF/Background';
+import type { Statistics } from '@APF/WebFilter';
 
 export default class BookmarkletFilter extends Filter {
   buildMessage: (destination: string, data?: object) => Message; // Bookmarklet: Not used - Needed to match signature of WebFilter
diff --git a/src/script/DataMigration.ts b/src/script/DataMigration.ts
index c3571708..23f762ea 100644
--- a/src/script/DataMigration.ts
+++ b/src/script/DataMigration.ts
@@ -1,6 +1,14 @@
 import Constants from '@APF/lib/Constants';
 import { booleanToNumber, getVersion, isVersionOlder } from '@APF/lib/helper';
 import WebConfig from '@APF/WebConfig';
+import type { WordOptions } from '@APF/lib/Word';
+
+export interface Migration {
+  async?: boolean;
+  name: string;
+  runOnImport: boolean;
+  version: string;
+}
 
 export default class DataMigration {
   cfg: WebConfig;
@@ -91,7 +99,7 @@ export default class DataMigration {
 
   // This will look at the version (from before the update) and perform data migrations if necessary
   async byVersion(oldVersion: string) {
-    const version = getVersion(oldVersion) as Version;
+    const version = getVersion(oldVersion);
     let migrated = false;
     for (const migration of (this.constructor as typeof DataMigration).migrations) {
       if (isVersionOlder(version, getVersion(migration.version))) {
diff --git a/src/script/Domain.ts b/src/script/Domain.ts
index 9cb2a369..2e753907 100644
--- a/src/script/Domain.ts
+++ b/src/script/Domain.ts
@@ -1,6 +1,16 @@
 import Constants from '@APF/lib/Constants';
 import type WebConfig from '@APF/WebConfig';
 
+export interface DomainCfg {
+  adv?: boolean;
+  deep?: boolean;
+  disabled?: boolean;
+  enabled?: boolean;
+  framesOff?: boolean;
+  framesOn?: boolean;
+  wordlist?: number;
+}
+
 export default class Domain {
   advanced: boolean;
   cfg: DomainCfg;
diff --git a/src/script/Environment.ts b/src/script/Environment.ts
new file mode 100644
index 00000000..ceac9968
--- /dev/null
+++ b/src/script/Environment.ts
@@ -0,0 +1,305 @@
+import type WebConfig from '@APF/WebConfig';
+
+export interface BrowserInfo {
+  browser:
+    | typeof Environment.BROWSER_CHROME
+    | typeof Environment.BROWSER_SAFARI
+    | typeof Environment.BROWSER_FIREFOX
+    | typeof Environment.BROWSER_EDGE
+    | typeof Environment.BROWSER_OPERA
+    | typeof Environment.BROWSER_UNKNOWN;
+  device: typeof Environment.DEVICE_DESKTOP | typeof Environment.DEVICE_TABLET | typeof Environment.DEVICE_PHONE;
+  os:
+    | typeof Environment.OS_ANDROID
+    | typeof Environment.OS_CHROMEOS
+    | typeof Environment.OS_IOS
+    | typeof Environment.OS_LINUX
+    | typeof Environment.OS_MACOS
+    | typeof Environment.OS_UNKNOWN
+    | typeof Environment.OS_WINDOWS;
+}
+
+type BaseTarget =
+  | typeof Environment.BUILD_TARGET_BOOKMARKLET
+  | typeof Environment.BUILD_TARGET_CHROME
+  | typeof Environment.BUILD_TARGET_FIREFOX;
+
+// open union: allows extra literal strings later (subclasses)
+type AnyTarget = BaseTarget | (string & {});
+
+export interface BuildInfo {
+  config: Partial<WebConfig>;
+  manifestVersion: number;
+  release: boolean;
+  target: AnyTarget;
+  version: string;
+}
+
+type UAData =
+  | {
+      brands?: Array<{ brand: string; version: string }>;
+      mobile?: boolean;
+      platform?: string;
+    }
+  | undefined;
+
+// __BUILD__ is injected by webpack from ROOT/.build.json
+/* eslint-disable-next-line @typescript-eslint/naming-convention */
+declare const __BUILD__: BuildInfo | undefined;
+const BUILD_DEFAULTS: BuildInfo = { config: {}, manifestVersion: 3, release: true, target: 'chrome', version: '1.0.0' };
+
+export default class Environment {
+  // Static constants
+  static readonly BROWSER_CHROME = 'chrome' as const;
+  static readonly BROWSER_EDGE = 'edge' as const;
+  static readonly BROWSER_FIREFOX = 'firefox' as const;
+  static readonly BROWSER_OPERA = 'opera' as const;
+  static readonly BROWSER_SAFARI = 'safari' as const;
+  static readonly BROWSER_UNKNOWN = 'unknown' as const;
+  static readonly BUILD_TARGET_BOOKMARKLET = 'bookmarklet' as const;
+  static readonly BUILD_TARGET_CHROME = 'chrome' as const;
+  static readonly BUILD_TARGET_FIREFOX = 'firefox' as const;
+  static readonly DEVICE_DESKTOP = 'desktop' as const;
+  static readonly DEVICE_PHONE = 'phone' as const;
+  static readonly DEVICE_TABLET = 'tablet' as const;
+  static readonly OS_ANDROID = 'android' as const;
+  static readonly OS_CHROMEOS = 'chromeos' as const;
+  static readonly OS_IOS = 'ios' as const;
+  static readonly OS_LINUX = 'linux' as const;
+  static readonly OS_MACOS = 'macos' as const;
+  static readonly OS_UNKNOWN = 'unknown' as const;
+  static readonly OS_WINDOWS = 'windows' as const;
+
+  // Static environment values - computed once and cached
+  private static readonly _BUILD_INFO: Readonly<BuildInfo> = Object.freeze(
+    typeof __BUILD__ === 'undefined' ? BUILD_DEFAULTS : __BUILD__,
+  );
+  private static readonly _BROWSER_INFO = Environment._computeBrowserInfoSafe();
+
+  // Static getters for browser info
+  static get browser(): BrowserInfo['browser'] {
+    return this._BROWSER_INFO.browser;
+  }
+  static get os(): BrowserInfo['os'] {
+    return this._BROWSER_INFO.os;
+  }
+  static get device(): BrowserInfo['device'] {
+    return this._BROWSER_INFO.device;
+  }
+
+  // Static getters for build info
+  static get buildTarget(): BuildInfo['target'] {
+    return this._BUILD_INFO.target;
+  }
+
+  static get manifestVersion(): BuildInfo['manifestVersion'] {
+    return this._BUILD_INFO.manifestVersion;
+  }
+
+  static get release(): BuildInfo['release'] {
+    return this._BUILD_INFO.release;
+  }
+
+  static get version(): BuildInfo['version'] {
+    return this._BUILD_INFO.version;
+  }
+
+  static get config(): BuildInfo['config'] {
+    return this._BUILD_INFO.config;
+  }
+
+  // Browser target static helpers
+  static get isChromeTarget() {
+    return this.buildTarget === this.BUILD_TARGET_CHROME;
+  }
+
+  static get isFirefoxTarget() {
+    return this.buildTarget === this.BUILD_TARGET_FIREFOX;
+  }
+
+  static get isBookmarkletTarget() {
+    return this.buildTarget === this.BUILD_TARGET_BOOKMARKLET;
+  }
+
+  // Build environment static helpers
+  static get isProduction() {
+    return this.release;
+  }
+
+  static get isDevelopment() {
+    return !this.isProduction;
+  }
+
+  // Device type static helpers
+  static get isDesktop() {
+    return this.device === this.DEVICE_DESKTOP;
+  }
+
+  static get isTablet() {
+    return this.device === this.DEVICE_TABLET;
+  }
+
+  static get isPhone() {
+    return this.device === this.DEVICE_PHONE;
+  }
+
+  static get isMobile() {
+    return this.isTablet || this.isPhone;
+  }
+
+  // Browser static helpers
+  static get isChrome() {
+    return this.browser === this.BROWSER_CHROME;
+  }
+
+  static get isFirefox() {
+    return this.browser === this.BROWSER_FIREFOX;
+  }
+
+  static get isSafari() {
+    return this.browser === this.BROWSER_SAFARI;
+  }
+
+  static get isEdge() {
+    return this.browser === this.BROWSER_EDGE;
+  }
+
+  static get isOpera() {
+    return this.browser === this.BROWSER_OPERA;
+  }
+
+  // OS static helpers
+  static get isWindows() {
+    return this.os === this.OS_WINDOWS;
+  }
+
+  static get isMacOS() {
+    return this.os === this.OS_MACOS;
+  }
+
+  static get isLinux() {
+    return this.os === this.OS_LINUX;
+  }
+
+  static get isAndroid() {
+    return this.os === this.OS_ANDROID;
+  }
+
+  static get isIOS() {
+    return this.os === this.OS_IOS;
+  }
+
+  static get isChromeOS() {
+    return this.os === this.OS_CHROMEOS;
+  }
+
+  // Manifest version static helpers
+  static get isManifestV2() {
+    return this.manifestVersion === 2;
+  }
+
+  static get isManifestV3() {
+    return this.manifestVersion === 3;
+  }
+
+  private static _computeBrowserInfoSafe(): BrowserInfo {
+    const unknown: BrowserInfo = { browser: this.BROWSER_UNKNOWN, os: this.OS_UNKNOWN, device: this.DEVICE_DESKTOP };
+    try {
+      if (typeof navigator === 'undefined') {
+        return unknown;
+      }
+      return this._computeBrowserInfo();
+    } catch {
+      return unknown;
+    }
+  }
+
+  private static _computeBrowserInfo(): BrowserInfo {
+    const ua = navigator.userAgent || '';
+    const uaData = (navigator as any).userAgentData as UAData;
+
+    // iPadOS heuristic (handles Safari reporting MacIntel)
+    const isiPadByPlatform = navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1;
+    const isiPadByUA = /\biPad\b/i.test(ua);
+    const isiPadByCH = (uaData?.platform === 'macOS' || uaData?.platform === 'Mac OS') && navigator.maxTouchPoints > 1;
+    const isiPadHeuristic = isiPadByPlatform || isiPadByUA || isiPadByCH;
+
+    // OS detection
+    let os: BrowserInfo['os'] = this.OS_UNKNOWN;
+    if (/Windows/i.test(ua)) os = this.OS_WINDOWS;
+    else if (/Android/i.test(ua)) os = this.OS_ANDROID;
+    else if (/iPhone|iPod/i.test(ua)) os = this.OS_IOS;
+    else if (isiPadHeuristic) os = this.OS_IOS;
+    else if (/Mac/i.test(ua)) os = this.OS_MACOS;
+    else if (/CrOS/i.test(ua)) os = this.OS_CHROMEOS;
+    else if (/Linux/i.test(ua)) os = this.OS_LINUX;
+
+    // Browser detection (filter "Not/A Brand")
+    const brands = (uaData?.brands ?? []).map((b) => b.brand.toLowerCase()).filter((b) => !/not.?a.?brand/i.test(b));
+    const hasBrand = (name: string) => brands.some((b) => b.includes(name));
+
+    let browser: BrowserInfo['browser'] = this.BROWSER_UNKNOWN;
+    if (hasBrand('edge') || /Edg(?:e|A|iOS)?\//i.test(ua)) {
+      browser = this.BROWSER_EDGE;
+    } else if (hasBrand('opera') || /OPR\/|Opera/i.test(ua)) {
+      browser = this.BROWSER_OPERA;
+    } else if (hasBrand('chrome') || /Chrome\/|CriOS\//i.test(ua)) {
+      if (!/OPR\/|Edg(?:e|A|iOS)?\//i.test(ua)) browser = this.BROWSER_CHROME;
+    } else if (/FxiOS\/|Firefox\//i.test(ua)) {
+      browser = this.BROWSER_FIREFOX;
+    } else if (hasBrand('safari') || (/Safari\//i.test(ua) && !/Chrome|Chromium|CriOS|FxiOS|Edg|OPR/i.test(ua))) {
+      browser = this.BROWSER_SAFARI;
+    }
+
+    // Device type
+    const chMobile = uaData?.mobile;
+    const isTouch =
+      (typeof matchMedia === 'function' &&
+        (() => {
+          try {
+            return matchMedia('(pointer: coarse)').matches;
+          } catch {
+            return false;
+          }
+        })()) ||
+      (typeof navigator.maxTouchPoints === 'number' && navigator.maxTouchPoints > 1);
+
+    const viewportShortSide =
+      typeof window !== 'undefined' ? Math.min(window.innerWidth || 0, window.innerHeight || 0) : 0;
+
+    let device: BrowserInfo['device'] = this.DEVICE_DESKTOP;
+
+    if (os === this.OS_IOS) {
+      device = isiPadHeuristic ? this.DEVICE_TABLET : this.DEVICE_PHONE;
+    } else if (os === this.OS_ANDROID) {
+      const uaHasMobile = /\bMobile\b/i.test(ua);
+      const uaHasTabletWord = /\bTablet\b|\bPad\b/i.test(ua);
+      const androidIsTablet = uaHasTabletWord || !uaHasMobile;
+
+      if (chMobile === false) {
+        device = this.DEVICE_TABLET; // UA-CH says "not mobile" → treat as tablet
+      } else {
+        device = androidIsTablet ? this.DEVICE_TABLET : this.DEVICE_PHONE;
+      }
+    } else {
+      // Non–Android/iOS: prefer desktop; use touch + viewport as a hint
+      if (isTouch) {
+        if (viewportShortSide > 0 && viewportShortSide < 600) {
+          device = this.DEVICE_PHONE;
+        } else if (viewportShortSide >= 600) {
+          device = this.DEVICE_TABLET;
+        } else {
+          device = this.DEVICE_DESKTOP;
+        }
+      } else {
+        device = this.DEVICE_DESKTOP;
+      }
+    }
+
+    return { browser, os, device };
+  }
+
+  constructor() {
+    throw new Error('Environment is a static class and cannot be instantiated');
+  }
+}
diff --git a/src/script/OptionPage.ts b/src/script/OptionPage.ts
index ffae7a1c..79b772e3 100644
--- a/src/script/OptionPage.ts
+++ b/src/script/OptionPage.ts
@@ -1,7 +1,7 @@
 import Constants from '@APF/lib/Constants';
 import WebConfig from '@APF/WebConfig';
 import Filter from '@APF/lib/Filter';
-import Domain from '@APF/Domain';
+import Domain, { type DomainCfg } from '@APF/Domain';
 import OptionAuth from '@APF/OptionAuth';
 import DataMigration from '@APF/DataMigration';
 import Bookmarklet from '@APF/bookmarklet';
@@ -21,6 +21,16 @@ import {
   timeForFileName,
   upperCaseFirst,
 } from '@APF/lib/helper';
+import type { Message } from '@APF/Background';
+import type { Statistics } from '@APF/WebFilter';
+import type { WordOptions } from '@APF/lib/Word';
+
+export interface ConfirmModalSettings {
+  backup?: boolean;
+  content?: string;
+  title?: string;
+  titleClass?: string;
+}
 
 const logger = new Logger('OptionPage');
 
@@ -1658,7 +1668,7 @@ export default class OptionPage {
     const wordsSelect = document.getElementById('wordList') as HTMLSelectElement;
 
     // Workaround for remove filter method
-    if (this.filter.cfg.filterWordList && this.filter.cfg.filterMethod === 2) {
+    if (this.filter.cfg.filterWordList && this.filter.cfg.filterMethod === this.Class.Constants.FILTER_METHODS.REMOVE) {
       wordlistFilter = new this.Class.Filter();
       // Works because we are only changing a native value (filterMethod: number)
       wordlistFilter.cfg = new this.Class.Config(Object.assign({}, this.cfg, { filterMethod: 0 }));
@@ -2177,7 +2187,7 @@ export default class OptionPage {
 
   setHelpVersion() {
     const helpVersion = document.getElementById('helpVersion') as HTMLAnchorElement;
-    helpVersion.textContent = this.cfg._buildInfo.version;
+    helpVersion.textContent = this.cfg._env.version;
   }
 
   setupEventListeners() {
diff --git a/src/script/Popup.ts b/src/script/Popup.ts
index c7022920..0f0aa2cb 100644
--- a/src/script/Popup.ts
+++ b/src/script/Popup.ts
@@ -5,6 +5,9 @@ import Page from '@APF/Page';
 import Logger from '@APF/lib/Logger';
 import Translation from '@APF/Translation';
 import { sendMessageWithRetry } from '@APF/lib/helper';
+import type { Summary } from '@APF/WebFilter';
+import type { BackgroundData, Message } from '@APF/Background';
+
 const logger = new Logger('Popup');
 
 export default class Popup {
@@ -359,10 +362,8 @@ export default class Popup {
     return (
       !this.domain.hostname ||
       this.Class.Page.disabledProtocols.test(this.url.protocol) ||
-      (this.cfg._buildInfo.target == this.Class.Constants.BUILD_TARGET_CHROME &&
-        this.Class.Page.disabledChromePages.includes(this.domain.hostname)) ||
-      (this.cfg._buildInfo.target == this.Class.Constants.BUILD_TARGET_FIREFOX &&
-        this.Class.Page.disabledFirefoxPages.includes(this.domain.hostname))
+      (this.cfg._env.isChromeTarget && this.Class.Page.disabledChromePages.includes(this.domain.hostname)) ||
+      (this.cfg._env.isFirefoxTarget && this.Class.Page.disabledFirefoxPages.includes(this.domain.hostname))
     );
   }
 
diff --git a/src/script/WebConfig.ts b/src/script/WebConfig.ts
index d57a5fd4..5e8b9414 100644
--- a/src/script/WebConfig.ts
+++ b/src/script/WebConfig.ts
@@ -3,16 +3,14 @@ import { prettyPrintArray, removeFromArray, sortObjectKeys, stringArray } from '
 import Logger from '@APF/lib/Logger';
 import Translation from '@APF/Translation';
 import Constants from '@APF/lib/Constants';
+import Environment from '@APF/Environment';
+import type { DomainCfg } from '@APF/Domain';
 
-// __BUILD__ is injected by webpack from ROOT/.build.json
-/* eslint-disable-next-line @typescript-eslint/naming-convention */
-declare const __BUILD__: BuildInfo;
-const BUILD_DEFAULTS: BuildInfo = { config: {}, manifestVersion: 3, release: true, target: 'chrome', version: '1.0.0' };
 const logger = new Logger('WebConfig');
 
 export default class WebConfig extends Config {
-  _buildInfo: BuildInfo;
   _defaultsLoaded: string[];
+  _env: typeof Environment;
   _lastSplitKeys: { [key: string]: number };
   collectStats: boolean;
   contextMenu: boolean;
@@ -30,6 +28,9 @@ export default class WebConfig extends Config {
   static get Constants() {
     return Constants;
   }
+  static get Environment() {
+    return Environment;
+  }
   get Class() {
     return this.constructor as typeof WebConfig;
   }
@@ -39,7 +40,6 @@ export default class WebConfig extends Config {
     return logger;
   }
 
-  static readonly BUILD = typeof __BUILD__ == 'undefined' ? BUILD_DEFAULTS : __BUILD__;
   static readonly _webDefaults = {
     collectStats: true,
     contextMenu: true,
@@ -335,7 +335,7 @@ export default class WebConfig extends Config {
     // Apply the Config defaults
     super(config);
 
-    this._buildInfo = this.Class.BUILD;
+    this._env = this.Class.Environment;
 
     this.log.setLevel(this.loggingLevel);
 
@@ -361,12 +361,7 @@ export default class WebConfig extends Config {
   }
 
   localizeDefaults() {
-    if (
-      this._buildInfo.target === this.Class.Constants.BUILD_TARGET_BOOKMARKLET ||
-      !this._defaultsLoaded ||
-      !this._defaultsLoaded.length
-    )
-      return;
+    if (this._env.isBookmarkletTarget || !this._defaultsLoaded || !this._defaultsLoaded.length) return;
 
     const translation = new Translation('common', this.language);
 
diff --git a/src/script/WebFilter.ts b/src/script/WebFilter.ts
index 452c8455..27f4e6c8 100644
--- a/src/script/WebFilter.ts
+++ b/src/script/WebFilter.ts
@@ -6,6 +6,29 @@ import Page from '@APF/Page';
 import WebConfig from '@APF/WebConfig';
 import Logger from '@APF/lib/Logger';
 import type Word from '@APF/lib/Word';
+import type { BackgroundData, Message } from '@APF/Background';
+
+export interface Statistics {
+  startedAt?: number;
+  words: WordStatistics;
+}
+
+export interface Summary {
+  [word: string]: {
+    filtered: string;
+    count: number;
+  };
+}
+
+export interface WordStatistic {
+  text: number;
+  total?: number;
+}
+
+export interface WordStatistics {
+  [word: string]: WordStatistic;
+}
+
 const logger = new Logger('WebFilter');
 
 export default class WebFilter extends Filter {
diff --git a/src/script/entry/bookmarklet.ts b/src/script/entry/bookmarklet.ts
index ae49961f..444dadaf 100644
--- a/src/script/entry/bookmarklet.ts
+++ b/src/script/entry/bookmarklet.ts
@@ -7,7 +7,7 @@ import BookmarkletFilter from '@APF/BookmarkletFilter';
 const config = WebConfig._defaults as WebConfig;
 /* @preserve - End User Config */
 
-console.log(`[APF Bookmarklet] Activated (version ${WebConfig.BUILD.version})`);
+console.log(`[APF Bookmarklet] Activated (version ${WebConfig.Environment.version})`);
 if (typeof window !== 'undefined' && !(<any>window).apfBookmarklet) {
   (<any>window).apfBookmarklet = true;
   console.log('[APF Bookmarklet] Running');
diff --git a/src/script/lib/Config.ts b/src/script/lib/Config.ts
index 492f5627..d616b3d1 100644
--- a/src/script/lib/Config.ts
+++ b/src/script/lib/Config.ts
@@ -1,4 +1,5 @@
 import Constants from './Constants';
+import type { WordOptions } from './Word';
 
 export default class Config {
   censorCharacter: string;
diff --git a/src/script/lib/Constants.ts b/src/script/lib/Constants.ts
index 75ecdd95..480ab408 100644
--- a/src/script/lib/Constants.ts
+++ b/src/script/lib/Constants.ts
@@ -4,9 +4,6 @@ import { upperCaseFirst } from './helper';
 export default class Constants {
   // Named Constants
   static readonly ALL_WORDS_WORDLIST_ID = 0;
-  static readonly BUILD_TARGET_BOOKMARKLET = 'bookmarklet';
-  static readonly BUILD_TARGET_CHROME = 'chrome';
-  static readonly BUILD_TARGET_FIREFOX = 'firefox';
   static readonly DOMAIN_MODES = { NORMAL: 0, ADVANCED: 1, DEEP: 2 };
   static readonly FALSE = 0;
   static readonly FILTER_METHODS = { CENSOR: 0, SUBSTITUTE: 1, REMOVE: 2, OFF: 3 };
diff --git a/src/script/lib/Filter.ts b/src/script/lib/Filter.ts
index 322a6895..c4e1848b 100644
--- a/src/script/lib/Filter.ts
+++ b/src/script/lib/Filter.ts
@@ -1,9 +1,15 @@
 import Constants from './Constants';
-import Word from './Word';
+import Word, { type WordOptions } from './Word';
 import Wordlist from './Wordlist';
 import Config from './Config';
 import { randomArrayElement } from './helper';
 
+export interface ReplaceTextResult {
+  filtered: string;
+  modified: boolean;
+  original: string;
+}
+
 export default class Filter {
   allowlist: string[];
   cfg: Config;
diff --git a/src/script/lib/Word.ts b/src/script/lib/Word.ts
index edc8be52..e381e21c 100644
--- a/src/script/lib/Word.ts
+++ b/src/script/lib/Word.ts
@@ -1,6 +1,16 @@
 import Constants from './Constants';
 import Config from './Config';
 
+export interface WordOptions {
+  _filterMethod?: number; // This should not be stored in the config. Only there for new Word
+  case?: number;
+  lists?: number[];
+  matchMethod: number;
+  repeat: number;
+  separators?: number;
+  sub: string;
+}
+
 export default class Word {
   _filterMethod: number;
   case?: number;
diff --git a/src/script/lib/globals.d.ts b/src/script/lib/globals.d.ts
deleted file mode 100644
index 8ad18e0b..00000000
--- a/src/script/lib/globals.d.ts
+++ /dev/null
@@ -1,114 +0,0 @@
-interface BackgroundData {
-  disabledTab?: boolean;
-}
-
-interface BackgroundStorage {
-  tabs?: {
-    [tabId: number]: TabStorageOptions;
-  };
-}
-
-interface BuildInfo {
-  config: any;
-  manifestVersion: number;
-  release: boolean;
-  target: string;
-  version: string;
-}
-
-interface ConfirmModalSettings {
-  backup?: boolean;
-  content?: string;
-  title?: string;
-  titleClass?: string;
-}
-
-interface DomainCfg {
-  adv?: boolean;
-  deep?: boolean;
-  disabled?: boolean;
-  enabled?: boolean;
-  framesOff?: boolean;
-  framesOn?: boolean;
-  wordlist?: number;
-}
-
-interface Message {
-  advanced?: boolean;
-  backgroundData?: boolean;
-  counter?: number;
-  deep?: boolean;
-  destination: string;
-  disabled?: boolean;
-  enableTab?: boolean;
-  forceUpdate?: boolean;
-  getStatus?: boolean;
-  globalVariable?: string;
-  iframe?: boolean;
-  popup?: boolean;
-  source: string;
-  status?: number;
-  summary?: Summary;
-  tabId?: number;
-  updateContextMenus?: boolean;
-  urlUpdate?: string;
-}
-
-interface Migration {
-  async?: boolean;
-  name: string;
-  runOnImport: boolean;
-  version: string;
-}
-
-interface ReplaceTextResult {
-  filtered: string;
-  modified: boolean;
-  original: string;
-}
-
-interface Statistics {
-  startedAt?: number;
-  words: WordStatistics;
-}
-
-interface Summary {
-  [word: string]: {
-    filtered: string;
-    count: number;
-  };
-}
-
-interface TabStorageOptions {
-  counters?: { number?: number };
-  disabled?: boolean;
-  disabledOnce?: number; // NOT_SET: 0, DISABLED: 1, WILL_DISABLE: 2
-  id?: number;
-  registeredAt?: number;
-  status?: number;
-}
-
-interface Version {
-  major: number;
-  minor: number;
-  patch: number;
-}
-
-interface WordOptions {
-  _filterMethod?: number; // This should not be stored in the config. Only there for new Word
-  case?: number;
-  lists?: number[];
-  matchMethod: number;
-  repeat: number;
-  separators?: number;
-  sub: string;
-}
-
-interface WordStatistic {
-  text: number;
-  total?: number;
-}
-
-interface WordStatistics {
-  [word: string]: WordStatistic;
-}
diff --git a/src/script/lib/helper.ts b/src/script/lib/helper.ts
index 5a1718a6..34ecfc6e 100644
--- a/src/script/lib/helper.ts
+++ b/src/script/lib/helper.ts
@@ -1,5 +1,11 @@
 import Constants from './Constants';
 
+export interface Version {
+  major: number;
+  minor: number;
+  patch: number;
+}
+
 export function booleanToNumber(value: boolean): number {
   return value ? Constants.TRUE : Constants.FALSE;
 }
@@ -259,11 +265,11 @@ export function upperCaseFirst(str: string, lowerCaseRest: boolean = true): stri
  * @param fallbackResponse - Default response if all retries fail
  * @returns Promise that resolves with the response
  */
-export function sendMessageWithRetry<tResponse = any>(
+export function sendMessageWithRetry<TResponse = any>(
   message: any,
   maxRetries: number = 3,
-  fallbackResponse?: tResponse,
-): Promise<tResponse> {
+  fallbackResponse?: TResponse,
+): Promise<TResponse> {
   return new Promise((resolve) => {
     let attempts = 0;