diff --git a/build.gradle b/build.gradle
index a1001ac..1372252 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,7 +2,6 @@
 plugins {
     alias libs.plugins.androidApplication apply false
     alias libs.plugins.androidLibrary apply false
-    alias libs.plugins.kotlinAndroid apply false
     alias libs.plugins.composeCompiler apply false
     alias libs.plugins.dokka apply false
     alias libs.plugins.mavenPublish apply false
diff --git a/common.gradle b/common.gradle
index 8ac933f..663d010 100644
--- a/common.gradle
+++ b/common.gradle
@@ -19,10 +19,6 @@ android {
         }
     }
 
-    kotlinOptions {
-        jvmTarget = '1.8'
-    }
-
     lint {
         abortOnError = true
         warningsAsErrors = true
diff --git a/dev-app/build.gradle b/dev-app/build.gradle
index 46f9f27..735d319 100644
--- a/dev-app/build.gradle
+++ b/dev-app/build.gradle
@@ -1,6 +1,5 @@
 plugins {
     alias libs.plugins.androidApplication
-    alias libs.plugins.kotlinAndroid
     alias libs.plugins.composeCompiler
 }
 
@@ -22,7 +21,7 @@ android {
             minifyEnabled = true
             proguardFiles = [
                 "okhttp3-proguard-rules.txt",
-                getDefaultProguardFile('proguard-android.txt')
+                getDefaultProguardFile('proguard-android-optimize.txt')
             ]
             signingConfig = signingConfigs.debug
         }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index f5a1913..b349dbe 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,5 +1,5 @@
 [versions]
-agp = "8.13.0"
+agp = "9.0.0"
 kotlin = "2.1.21"
 core-ktx = "1.16.0"
 junit = "4.13.2"
@@ -35,7 +35,6 @@ okhttp-core = { group = "com.squareup.okhttp3", name = "okhttp", version = "4.12
 # GMA / IMA
 gma-ads = { group = "com.google.android.gms", name = "play-services-ads", version.ref = "gma" }
 ima-ads = { group = "com.google.ads.interactivemedia.v3", name = "interactivemedia", version.ref = "ima" }
-androidx-multidex = { group = "androidx.multidex", name = "multidex", version = "2.0.1" }
 androidx-constraintlayout = { group = "androidx.constraintlayout", name = "constraintlayout", version = "2.2.1" }
 androidx-media = { group = "androidx.media", name = "media", version = "1.7.0" }
 androidx-browser = { group = "androidx.browser", name = "browser", version = "1.8.0" }
@@ -54,7 +53,6 @@ mockk-agent = { group = "io.mockk", name = "mockk-agent", version.ref = "mockkVe
 [plugins]
 androidApplication = { id = "com.android.application", version.ref = "agp" }
 androidLibrary = { id = "com.android.library", version.ref = "agp" }
-kotlinAndroid = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
 composeCompiler = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
 spotless = { id = "com.diffplug.spotless", version = "7.0.4" }
 dokka = { id = "org.jetbrains.dokka", version = "2.0.0" }
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 1b33c55..f8e1ee3 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index bad7c24..19a6bde 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-9.2.0-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.3.0-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/gradlew b/gradlew
index 23d15a9..adff685 100755
--- a/gradlew
+++ b/gradlew
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 #
-# Copyright © 2015-2021 the original authors.
+# Copyright © 2015 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -114,7 +114,6 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -172,7 +171,6 @@ fi
 # For Cygwin or MSYS, switch paths to Windows format before running java
 if "$cygwin" || "$msys" ; then
     APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
-    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
 
     JAVACMD=$( cygpath --unix "$JAVACMD" )
 
@@ -212,7 +210,6 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
-        -classpath "$CLASSPATH" \
         -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
diff --git a/gradlew.bat b/gradlew.bat
index 5eed7ee..e509b2d 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -70,11 +70,10 @@ goto fail
 :execute
 @rem Setup the command line
 
-set CLASSPATH=
 
 
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
 
 :end
 @rem End local scope for the variables with windows NT shell
diff --git a/prebid/build.gradle b/prebid/build.gradle
index 4f52e52..af9acb3 100644
--- a/prebid/build.gradle
+++ b/prebid/build.gradle
@@ -1,6 +1,7 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias libs.plugins.androidLibrary
-    alias libs.plugins.kotlinAndroid
     alias libs.plugins.dokka
     alias libs.plugins.mavenPublish
 }
@@ -15,10 +16,10 @@ android {
 
     kotlin {
         explicitApi()
-    }
-
-    kotlinOptions {
-        freeCompilerArgs += [ "-opt-in=com.uid2.InternalUID2Api" ]
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+            optIn.add("com.uid2.InternalUID2Api")
+        }
     }
 }
 
diff --git a/prebid/src/main/java/com/uid2/prebid/UID2Prebid.kt b/prebid/src/main/java/com/uid2/prebid/UID2Prebid.kt
index a1b277c..d5277c7 100644
--- a/prebid/src/main/java/com/uid2/prebid/UID2Prebid.kt
+++ b/prebid/src/main/java/com/uid2/prebid/UID2Prebid.kt
@@ -121,14 +121,20 @@ public class UID2Prebid internal constructor(
      * Extension function to build a list containing the single [ExternalUserId] that is associated with UID2.
      */
     private fun String.toExternalUserIdList(): List<ExternalUserId> {
+        val source = if (manager.isEuid) {
+            USER_ID_SOURCE_EUID
+        } else {
+            USER_ID_SOURCE_UID2
+        }
         return listOf(
-            ExternalUserId(USER_ID_SOURCE, listOf(ExternalUserId.UniqueId(this, AGENT_TYPE_PERSON_ID))),
+            ExternalUserId(source, listOf(ExternalUserId.UniqueId(this, AGENT_TYPE_PERSON_ID))),
         )
     }
 
     private companion object {
         const val TAG = "UID2Prebid"
-        const val USER_ID_SOURCE = "uidapi.com"
+        const val USER_ID_SOURCE_UID2 = "uidapi.com"
+        const val USER_ID_SOURCE_EUID = "euid.eu"
 
         /**
          * "A person-based ID, i.e., that is the same across devices."
diff --git a/prebid/src/test/java/com/uid2/prebid/UID2PrebidTest.kt b/prebid/src/test/java/com/uid2/prebid/UID2PrebidTest.kt
index fec61fb..95771c0 100644
--- a/prebid/src/test/java/com/uid2/prebid/UID2PrebidTest.kt
+++ b/prebid/src/test/java/com/uid2/prebid/UID2PrebidTest.kt
@@ -48,6 +48,7 @@ class UID2PrebidTest {
         every { manager.getAdvertisingToken() }.returns(currentAdvertisingToken)
         every { manager.state }.returns(state)
         every { manager.logger }.returns(logger)
+        every { manager.isEuid }.returns(false)
     }
 
     @Test
@@ -73,7 +74,7 @@ class UID2PrebidTest {
         advanceUntilIdle()
 
         // Verify it was set on Prebid.
-        prebidExternalUserIdInteractor.assertLastToken(newToken1)
+        prebidExternalUserIdInteractor.assertLastToken(newToken1, "uidapi.com")
 
         // Refresh the token.
         val newToken2 = "refreshed-token-1"
@@ -81,7 +82,7 @@ class UID2PrebidTest {
         advanceUntilIdle()
 
         // Verify it was set on Prebid.
-        prebidExternalUserIdInteractor.assertLastToken(newToken2)
+        prebidExternalUserIdInteractor.assertLastToken(newToken2, "uidapi.com")
 
         // Refresh the token again.
         val newToken3 = "refreshed-token-2"
@@ -89,7 +90,40 @@ class UID2PrebidTest {
         advanceUntilIdle()
 
         // Verify it was set on Prebid.
-        prebidExternalUserIdInteractor.assertLastToken(newToken3)
+        prebidExternalUserIdInteractor.assertLastToken(newToken3, "uidapi.com")
+    }
+
+    @Test
+    fun `sets the source for EUID`() = runTest(testDispatcher) {
+        every { manager.isEuid }.returns(true)
+
+        val prebid = withPrebid().apply {
+            initialize()
+        }
+
+        // Start with an established token.
+        val newToken1 = "established-token"
+        state.emit(withEstablished(newToken1))
+        advanceUntilIdle()
+
+        // Verify it was set on Prebid.
+        prebidExternalUserIdInteractor.assertLastToken(newToken1, "euid.eu")
+
+        // Refresh the token.
+        val newToken2 = "refreshed-token-1"
+        state.emit(withRefreshed(newToken2))
+        advanceUntilIdle()
+
+        // Verify it was set on Prebid.
+        prebidExternalUserIdInteractor.assertLastToken(newToken2, "euid.eu")
+
+        // Refresh the token again.
+        val newToken3 = "refreshed-token-2"
+        state.emit(withRefreshed(newToken3))
+        advanceUntilIdle()
+
+        // Verify it was set on Prebid.
+        prebidExternalUserIdInteractor.assertLastToken(newToken3, "euid.eu")
     }
 
     @Test
@@ -111,7 +145,7 @@ class UID2PrebidTest {
             advanceUntilIdle()
 
             // Verify that it's been set on Prebid.
-            prebidExternalUserIdInteractor.assertLastToken(token)
+            prebidExternalUserIdInteractor.assertLastToken(token, "uidapi.com")
 
             // Emit the new state.
             state.emit(managerState)
@@ -148,10 +182,10 @@ class UID2PrebidTest {
         refreshResponseKey = "",
     )
 
-    private fun FakePrebidExternalUserIdInteractor.assertLastToken(advertisingToken: String) {
+    private fun FakePrebidExternalUserIdInteractor.assertLastToken(advertisingToken: String, source: String) {
         assertTrue(lastIds.isNotEmpty())
         lastIds.last().let {
-            assertEquals("uidapi.com", it.source)
+            assertEquals(source, it.source)
             assertEquals(1, it.uniqueIds.size)
             val id = it.uniqueIds[0]
             assertEquals(advertisingToken, id.id)
diff --git a/sdk/build.gradle b/sdk/build.gradle
index f4657a0..c9931b2 100644
--- a/sdk/build.gradle
+++ b/sdk/build.gradle
@@ -1,6 +1,7 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias libs.plugins.androidLibrary
-    alias libs.plugins.kotlinAndroid
     alias libs.plugins.dokka
     alias libs.plugins.mavenPublish
 }
@@ -29,10 +30,10 @@ android {
 
     kotlin {
         explicitApi()
-    }
-
-    kotlinOptions {
-        freeCompilerArgs += [ "-opt-in=com.uid2.InternalUID2Api" ]
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+            optIn.add("com.uid2.InternalUID2Api")
+        }
     }
 }
 
diff --git a/sdk/src/main/java/com/uid2/EUIDManager.kt b/sdk/src/main/java/com/uid2/EUIDManager.kt
index 10c8559..dbac326 100644
--- a/sdk/src/main/java/com/uid2/EUIDManager.kt
+++ b/sdk/src/main/java/com/uid2/EUIDManager.kt
@@ -100,18 +100,19 @@ public object EUIDManager {
         val logger = Logger(isLoggingEnabled)
 
         return instance ?: UID2Manager(
-            UID2Client(
+            client = UID2Client(
                 apiUrl = serverUrl,
                 session = networkSession,
                 applicationId = applicationId,
                 logger = logger,
             ),
-            storage,
-            TimeUtils,
-            InputUtils(),
-            Dispatchers.Default,
-            true,
-            logger,
+            storageManager = storage,
+            timeUtils = TimeUtils,
+            inputUtils = InputUtils(),
+            defaultDispatcher = Dispatchers.Default,
+            initialAutomaticRefreshEnabled = true,
+            isEuid = true,
+            logger = logger,
         ).apply {
             instance = this
         }
diff --git a/sdk/src/main/java/com/uid2/UID2Manager.kt b/sdk/src/main/java/com/uid2/UID2Manager.kt
index afa0691..4a7f70a 100644
--- a/sdk/src/main/java/com/uid2/UID2Manager.kt
+++ b/sdk/src/main/java/com/uid2/UID2Manager.kt
@@ -95,6 +95,7 @@ public class UID2Manager internal constructor(
     private val inputUtils: InputUtils,
     defaultDispatcher: CoroutineDispatcher,
     initialAutomaticRefreshEnabled: Boolean,
+    @property:InternalUID2Api public val isEuid: Boolean,
     @property:InternalUID2Api public val logger: Logger,
 ) {
     private val scope = CoroutineScope(defaultDispatcher + SupervisorJob())
@@ -614,6 +615,7 @@ public class UID2Manager internal constructor(
         private const val EXPIRATION_CHECK_TOLERANCE_MS = 50
 
         private var serverUrl: String = UID2_API_URL_PRODUCTION
+        private var isEuid: Boolean = true
         private var applicationId: String = APPLICATION_ID_DEFAULT
         private var networkSession: NetworkSession = DefaultNetworkSession()
         private var storageManager: StorageManager? = null
@@ -694,18 +696,19 @@ public class UID2Manager internal constructor(
             val logger = Logger(isLoggingEnabled)
 
             return instance ?: UID2Manager(
-                UID2Client(
+                client = UID2Client(
                     apiUrl = serverUrl,
                     session = networkSession,
                     applicationId = applicationId,
                     logger = logger,
                 ),
-                storage,
-                TimeUtils,
-                InputUtils(),
-                Dispatchers.Default,
-                true,
-                logger,
+                storageManager = storage,
+                timeUtils = TimeUtils,
+                inputUtils = InputUtils(),
+                defaultDispatcher = Dispatchers.Default,
+                initialAutomaticRefreshEnabled = true,
+                isEuid = false,
+                logger = logger,
             ).apply {
                 instance = this
             }
diff --git a/sdk/src/test/java/com/uid2/UID2ManagerTest.kt b/sdk/src/test/java/com/uid2/UID2ManagerTest.kt
index 32baba1..7407bad 100644
--- a/sdk/src/test/java/com/uid2/UID2ManagerTest.kt
+++ b/sdk/src/test/java/com/uid2/UID2ManagerTest.kt
@@ -87,7 +87,16 @@ class UID2ManagerTest {
             }
         }
 
-        val manager = UID2Manager(client, storageManager, timeUtils, inputUtils, testDispatcher, false, logger).apply {
+        val manager = UID2Manager(
+            client = client,
+            storageManager = storageManager,
+            timeUtils = timeUtils,
+            inputUtils = inputUtils,
+            defaultDispatcher = testDispatcher,
+            initialAutomaticRefreshEnabled = false,
+            isEuid = false,
+            logger = logger,
+        ).apply {
             this.checkExpiration = false
 
             // Add the required listeners.
@@ -238,7 +247,16 @@ class UID2ManagerTest {
     @Test
     fun `resets identity immediately after initialisation`() = runTest(testDispatcher) {
         // Create a new instance of the manager but *don't* allow it to finish initialising (loading previous identity)
-        val manager = UID2Manager(client, storageManager, timeUtils, inputUtils, testDispatcher, false, logger).apply {
+        val manager = UID2Manager(
+            client = client,
+            storageManager = storageManager,
+            timeUtils = timeUtils,
+            inputUtils = inputUtils,
+            defaultDispatcher = testDispatcher,
+            initialAutomaticRefreshEnabled = false,
+            isEuid = false,
+            logger = logger,
+        ).apply {
             onIdentityChangedListener = listener
             checkExpiration = false
         }
@@ -556,13 +574,14 @@ class UID2ManagerTest {
         initialCheckExpiration: Boolean = false,
     ): UID2Manager {
         return UID2Manager(
-            client,
-            storageManager,
-            timeUtils,
-            inputUtils,
-            dispatcher,
-            initialAutomaticRefreshEnabled,
-            logger,
+            client = client,
+            storageManager = storageManager,
+            timeUtils = timeUtils,
+            inputUtils = inputUtils,
+            defaultDispatcher = dispatcher,
+            initialAutomaticRefreshEnabled = initialAutomaticRefreshEnabled,
+            isEuid = false,
+            logger = logger,
         ).apply {
             onIdentityChangedListener = listener
             checkExpiration = initialCheckExpiration
diff --git a/securesignals-gma-dev-app/build.gradle b/securesignals-gma-dev-app/build.gradle
index 1a72d29..2c26d38 100644
--- a/securesignals-gma-dev-app/build.gradle
+++ b/securesignals-gma-dev-app/build.gradle
@@ -1,6 +1,7 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias libs.plugins.androidApplication
-    alias libs.plugins.kotlinAndroid
 }
 
 apply from:  rootProject.file("$rootDir/common.gradle")
@@ -22,6 +23,12 @@ android {
         }
     }
 
+    kotlin {
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+        }
+    }
+
     lint {
         disable 'GradleDependency'
     }
@@ -33,7 +40,6 @@ dependencies {
     implementation project(path: ':securesignals-gma')
     implementation(libs.gma.ads)
 
-    implementation(libs.androidx.multidex)
     implementation(libs.androidx.appcompat)
     implementation(libs.androidx.constraintlayout)
 }
diff --git a/securesignals-gma/build.gradle b/securesignals-gma/build.gradle
index 3de7a80..8322c7e 100644
--- a/securesignals-gma/build.gradle
+++ b/securesignals-gma/build.gradle
@@ -1,6 +1,7 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias libs.plugins.androidLibrary
-    alias libs.plugins.kotlinAndroid
     alias libs.plugins.mavenPublish
 }
 
@@ -21,6 +22,9 @@ android {
 
     kotlin {
         explicitApi()
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+        }
     }
 }
 
diff --git a/securesignals-ima-dev-app/build.gradle b/securesignals-ima-dev-app/build.gradle
index eaaf95d..86733ec 100644
--- a/securesignals-ima-dev-app/build.gradle
+++ b/securesignals-ima-dev-app/build.gradle
@@ -1,6 +1,7 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias libs.plugins.androidApplication
-    alias libs.plugins.kotlinAndroid
 }
 
 apply from:  rootProject.file("$rootDir/common.gradle")
@@ -22,6 +23,12 @@ android {
         }
     }
 
+    kotlin {
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+        }
+    }
+
     lint {
         disable 'GradleDependency', 'IconDipSize', 'IconDensities', 'RtlEnabled'
     }
@@ -38,7 +45,6 @@ dependencies {
     implementation(libs.androidx.activity.ktx)
     implementation(libs.androidx.constraintlayout)
 
-    implementation(libs.androidx.multidex)
     implementation(libs.androidx.browser)
     implementation(libs.androidx.media)
 }
diff --git a/securesignals-ima/build.gradle b/securesignals-ima/build.gradle
index c201329..bb1c6d5 100644
--- a/securesignals-ima/build.gradle
+++ b/securesignals-ima/build.gradle
@@ -1,6 +1,7 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias libs.plugins.androidLibrary
-    alias libs.plugins.kotlinAndroid
     alias libs.plugins.mavenPublish
 }
 
@@ -21,6 +22,9 @@ android {
 
     kotlin {
         explicitApi()
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_1_8
+        }
     }
 }