diff --git a/firebase-authexchange/firebase-authexchange.gradle b/firebase-authexchange/firebase-authexchange.gradle
deleted file mode 100644
index ade4db1e247..00000000000
--- a/firebase-authexchange/firebase-authexchange.gradle
+++ /dev/null
@@ -1,54 +0,0 @@
-// Copyright 2022 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-plugins {
-    id 'firebase-library'
-    id 'kotlin-android'
-}
-
-firebaseLibrary {
-    publishSources = true
-}
-
-android {
-    compileSdkVersion project.targetSdkVersion
-    defaultConfig {
-        targetSdkVersion project.targetSdkVersion
-        minSdkVersion 16
-        versionName version
-        multiDexEnabled true
-        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
-    }
-
-    testOptions {
-        unitTests {
-            includeAndroidResources = true
-        }
-    }
-}
-
-dependencies {
-    implementation project(':firebase-common')
-    implementation project(':firebase-common:ktx')
-    implementation project(':firebase-components')
-    implementation project(':firebase-authexchange-interop')
-
-    implementation 'androidx.annotation:annotation:1.5.0'
-    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
-
-    testImplementation 'androidx.test:core:1.5.0'
-    testImplementation "com.google.truth:truth:$googleTruthVersion"
-    testImplementation 'junit:junit:4.13.2'
-    testImplementation "org.robolectric:robolectric:$robolectricVersion"
-}
diff --git a/firebase-authexchange/firebase-authexchange.gradle.kts b/firebase-authexchange/firebase-authexchange.gradle.kts
new file mode 100644
index 00000000000..2057b3fa683
--- /dev/null
+++ b/firebase-authexchange/firebase-authexchange.gradle.kts
@@ -0,0 +1,49 @@
+plugins {
+  id("firebase-library")
+  kotlin("android")
+  kotlin("plugin.serialization") version "1.7.20"
+}
+
+firebaseLibrary {
+  publishSources = true
+}
+
+android {
+  val targetSdkVersion : Int by rootProject
+
+  compileSdk = targetSdkVersion
+  defaultConfig {
+    minSdk = 16
+    targetSdk = targetSdkVersion
+    multiDexEnabled = true
+    testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+  }
+
+  sourceSets {
+    getByName("main") {
+      java.srcDirs("src/main/kotlin")
+    }
+    getByName("test") {
+      java.srcDirs("src/test/kotlin")
+    }
+  }
+
+  testOptions.unitTests.isIncludeAndroidResources = true
+}
+
+dependencies {
+  implementation(project(":firebase-common"))
+  implementation(project(":firebase-common:ktx"))
+  implementation(project(":firebase-components"))
+  implementation(project(":firebase-authexchange-interop"))
+
+  implementation(libs.androidx.annotation)
+  implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.4.1")
+  implementation(libs.kotlin.stdlib)
+
+
+  testImplementation(libs.androidx.test.core)
+  testImplementation(libs.truth)
+  testImplementation(libs.junit)
+  testImplementation(libs.robolectric)
+}
diff --git a/firebase-authexchange/src/main/kotlin/com/google/firebase/authexchange/network/Routes.kt b/firebase-authexchange/src/main/kotlin/com/google/firebase/authexchange/network/Routes.kt
new file mode 100644
index 00000000000..d10c9a95bf8
--- /dev/null
+++ b/firebase-authexchange/src/main/kotlin/com/google/firebase/authexchange/network/Routes.kt
@@ -0,0 +1,105 @@
+package com.google.firebase.authexchange.network
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+/**
+ * Defines what an HTTP request may look like when interacting with the backend API for
+ * [FirebaseAuthExchange][com.google.firebase.authexchange.FirebaseAuthExchange].
+ */
+@Serializable internal sealed interface Request
+
+/** Defines what an HTTP response may look like when submitting a [Request]. */
+@Serializable internal sealed interface Response
+
+/**
+ * OIDC Credential.
+ *
+ * Useful for apps with external login already set-up, otherwise known as a headless OIDC flow.
+ *
+ * @property idToken JWT encoded OIDC token returned from a third party provider
+ */
+@Serializable internal data class ImplicitCredentialsP(val idToken: String)
+
+/**
+ * Auth Token that can be used to access certain Firebase Services.
+ *
+ * This is merely the proto type for the network layer, and is completely separate from the user
+ * facing [AuthExchangeToken][com.google.firebase.authexchange.AuthExchangeToken].
+ *
+ * @property accessToken signed JWT containing claims that identify a user
+ * @property timeToLive the duration from the time this token is minted until its expiration
+ */
+@Serializable
+internal data class AuthExchangeTokenP(
+  val accessToken: String,
+  @SerialName("ttl") val timeToLive: String
+)
+
+/**
+ * Request header for the `/ExchangeInstallationAuthToken` endpoint.
+ *
+ * @see ExchangeTokenResponseP
+ *
+ * @property token relative resource name of the audience project and location
+ * @property installationAuthToken the installation token issued to the app
+ */
+@Serializable
+internal data class ExchangeInstallationAuthTokenRequestP(
+  val token: String,
+  val installationAuthToken: String
+) : Request
+
+/**
+ * Request header for the `/ExchangeCustomToken` endpoint.
+ *
+ * @see ExchangeTokenResponseP
+ *
+ * @property token relative resource name of the audience project and location
+ * @property customToken a custom JWT token signed with the developer's credentials
+ */
+@Serializable
+internal data class ExchangeCustomTokenRequestP(val token: String, val customToken: String) :
+  Request
+
+/**
+ * Request header for the `/ExchangeOidcToken` endpoint.
+ *
+ * @see ExchangeOidcTokenResponseP
+ *
+ * @property token relative resource name of the audience project and location
+ * @property providerId the display name or id of the OIDC provider
+ * @property implicitCredentials JWT token from the OIDC provider, provided by the developer
+ */
+@Serializable
+internal data class ExchangeOidcTokenRequestP(
+  val token: String,
+  val providerId: String,
+  val implicitCredentials: ImplicitCredentialsP
+) : Request
+
+/**
+ * Response header for endpoints that just expect an [AuthExchangeTokenP].
+ *
+ * @see ExchangeCustomTokenRequestP
+ * @see ExchangeInstallationAuthTokenRequestP
+ *
+ * @property token auth token returned by the backend
+ */
+@Serializable internal data class ExchangeTokenResponseP(val token: AuthExchangeTokenP) : Response
+
+/**
+ * Response header for the `/ExchangeOidcToken` endpoint.
+ *
+ * @see ExchangeOidcTokenRequestP
+ *
+ * @property authExchangeToken auth token returned by the backend
+ * @property oidcIdToken OAuth id token received from the OIDC provider
+ * @property oidcRefreshToken optional OAuth refresh token received from the OIDC provider
+ */
+@Serializable
+internal data class ExchangeOidcTokenResponseP(
+  val authExchangeToken: AuthExchangeTokenP,
+  val oidcIdToken: String,
+  val oidcRefreshToken: String? = null
+) : Response