diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index c5a4c858b..1ad8f64d0 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -18,9 +18,13 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [20.x]
+        node-version: [22.x]
         mongodb-version: [4]
     steps:
+      - name: Remove temporary files
+        run: sudo rm -rf /tmp/*
+      - name: Remove hosted tool cache
+        run: sudo rm -rf /opt/hostedtoolcache
       - name: Git checkout
         uses: actions/checkout@v4
       - name: Use Node.js ${{ matrix.node-version }}
@@ -29,7 +33,7 @@ jobs:
           node-version: ${{ matrix.node-version }}
           cache: "npm"
       - name: Start MongoDB
-        uses: supercharge/mongodb-github-action@1.10.0
+        uses: supercharge/mongodb-github-action@1.11.0
         with:
           mongodb-version: ${{ matrix.mongodb-version }}
       - name: Download localisations
diff --git a/helpers/mock-agent/endpoint-auth.js b/helpers/mock-agent/endpoint-auth.js
index 48424424b..c5c60ce96 100644
--- a/helpers/mock-agent/endpoint-auth.js
+++ b/helpers/mock-agent/endpoint-auth.js
@@ -11,6 +11,17 @@ export const mockClient = () => {
 
   const origin = "https://auth-endpoint.example";
 
+  // Client metadata
+  agent
+    .get(origin)
+    .intercept({ path: "/id" })
+    .reply(200, {
+      client_id: `${origin}/id`,
+      client_name: "Client with metadata",
+      client_uri: origin,
+      logo_uri: `${origin}/logo.png`,
+    });
+
   // Client information (h-x-app)
   agent
     .get(origin)
diff --git a/packages/endpoint-auth/lib/client.js b/packages/endpoint-auth/lib/client.js
index d74eafd2d..0e6893a5a 100644
--- a/packages/endpoint-auth/lib/client.js
+++ b/packages/endpoint-auth/lib/client.js
@@ -1,37 +1,27 @@
 import { mf2 } from "microformats-parser";
 
 /**
- * Get client information
- * @param {string} client_id - Client URL
- * @returns {Promise<object>} Information about the client
- * @see {@link https://indieauth.spec.indieweb.org/#client-information-discovery}
+ * Get client information from application Microformat
+ * @param {string} body - Response body
+ * @param {object} client - Fallback client information
+ * @returns {object} Client information
+ * @deprecated since 11 July 2024
+ * @see {@link https://indieauth.spec.indieweb.org/20220212/#application-information}
  */
-export const getClientInformation = async (client_id) => {
-  let client = {
-    name: new URL(client_id).host,
-    url: client_id,
-  };
-
-  const clientResponse = await fetch(client_id);
-  if (!clientResponse.ok) {
-    return client;
-  }
-
-  const body = await clientResponse.text();
-
-  // If response contains microformats, use available derived values
-  const { items } = mf2(body, { baseUrl: client_id });
+export const getApplicationInformation = (body, client) => {
+  const { items } = mf2(body, { baseUrl: client.url });
   for (const item of items) {
     const { properties, type } = item;
 
     if (/^h-(?:x-)?app$/.test(type[0])) {
-      // If no URL property, use `client_id`
+      // If no URL property, use baseUrl
       if (!properties.url) {
-        properties.url = [client_id];
+        properties.url = [client.url];
       }
 
-      // If has URL property, only continue if matches `client_id`
-      if (!properties.url?.includes(client_id)) {
+      // Check that URL property matches `client_id`. Note that this isn’t for
+      // authentication, but to ensure only relevant client metadata is returned
+      if (!properties.url?.includes(client.url)) {
         continue;
       }
 
@@ -48,3 +38,54 @@ export const getClientInformation = async (client_id) => {
 
   return client;
 };
+
+/**
+ * Get client information from client metadata
+ * @param {string} body - Response body
+ * @param {object} client - Fallback client information
+ * @returns {object} Client information
+ * @see {@link https://indieauth.spec.indieweb.org/#client-metadata}
+ */
+export const getClientMetadata = (body, client) => {
+  const json = JSON.parse(body);
+
+  // Client metadata MUST include `client_id`
+  if (!Object.hasOwn(json, "client_id")) {
+    throw new Error("Client metadata JSON not valid");
+  }
+
+  return {
+    logo: json.logo_uri,
+    name: json.client_name || client.name,
+    url: json.client_uri || client.url,
+  };
+};
+
+/**
+ * Get client information
+ * @param {string} clientId - Client ID
+ * @returns {Promise<object>} Information about the client
+ * @see {@link https://indieauth.spec.indieweb.org/#client-information-discovery}
+ */
+export const getClientInformation = async (clientId) => {
+  let client = {
+    name: new URL(clientId).host,
+    url: new URL(clientId).href,
+  };
+
+  const clientResponse = await fetch(clientId);
+  if (!clientResponse.ok) {
+    // Use information derived from clientId
+    return client;
+  }
+
+  const body = await clientResponse.text();
+
+  try {
+    // Use information from client JSON metadata
+    return getClientMetadata(body, client);
+  } catch {
+    // Use information from client HTML microformats (deprecated)
+    return getApplicationInformation(body, client);
+  }
+};
diff --git a/packages/endpoint-auth/test/unit/client.js b/packages/endpoint-auth/test/unit/client.js
index ccef22327..469102820 100644
--- a/packages/endpoint-auth/test/unit/client.js
+++ b/packages/endpoint-auth/test/unit/client.js
@@ -6,6 +6,18 @@ import { getClientInformation } from "../../lib/client.js";
 await mockAgent("endpoint-auth");
 
 describe("endpoint-auth/lib/client", () => {
+  it("Gets client information (from metadata)", async () => {
+    const result = await getClientInformation(
+      "https://auth-endpoint.example/id",
+    );
+
+    assert.deepEqual(result, {
+      logo: "https://auth-endpoint.example/logo.png",
+      name: "Client with metadata",
+      url: "https://auth-endpoint.example",
+    });
+  });
+
   it("Gets client information (has h-x-app microformat)", async () => {
     const result = await getClientInformation("https://auth-endpoint.example/");
 
diff --git a/packages/indiekit/lib/controllers/client.js b/packages/indiekit/lib/controllers/client.js
new file mode 100644
index 000000000..49722beba
--- /dev/null
+++ b/packages/indiekit/lib/controllers/client.js
@@ -0,0 +1,13 @@
+export const get = async (request, response) => {
+  const { name: client_name, url: client_uri } = request.app.locals.application;
+  const { href: client_id } = new URL("id", client_uri);
+  const { href: logo_uri } = new URL("assets/app-icon-512-any.png", client_uri);
+
+  response.set("Cache-Control", "public, max-age=604800"); // 7 days
+  return response.type("application/json").json({
+    client_id,
+    client_name,
+    client_uri,
+    logo_uri,
+  });
+};
diff --git a/packages/indiekit/lib/indieauth.js b/packages/indiekit/lib/indieauth.js
index af71dc6b1..65a97ff61 100644
--- a/packages/indiekit/lib/indieauth.js
+++ b/packages/indiekit/lib/indieauth.js
@@ -79,14 +79,16 @@ export const IndieAuth = class {
     return async (request, response) => {
       try {
         const { application } = request.app.locals;
-        this.clientId = getCanonicalUrl(application.url);
+        const applicationUrl = getCanonicalUrl(application.url);
+        const { href: clientId } = new URL("id", applicationUrl);
+        const { href: callbackUrl } = new URL("session/auth", applicationUrl);
 
-        const callbackUrl = `${application.url}/session/auth`;
         const { redirect } = request.query;
         this.redirectUri = redirect
           ? `${callbackUrl}?redirect=${redirect}`
           : `${callbackUrl}`;
 
+        this.clientId = clientId;
         const state = generateState(this.clientId, this.iv);
         const authUrl = await this.getAuthUrl(
           application.authorizationEndpoint,
diff --git a/packages/indiekit/lib/routes.js b/packages/indiekit/lib/routes.js
index 61923c70c..af0743c53 100644
--- a/packages/indiekit/lib/routes.js
+++ b/packages/indiekit/lib/routes.js
@@ -3,6 +3,7 @@ import express from "express";
 import { assetsPath } from "@indiekit/frontend";
 import rateLimit from "express-rate-limit";
 import * as assetsController from "./controllers/assets.js";
+import * as clientController from "./controllers/client.js";
 import * as feedController from "./controllers/feed.js";
 import * as homepageController from "./controllers/homepage.js";
 import * as manifestController from "./controllers/manifest.js";
@@ -70,6 +71,9 @@ export const routes = (indiekitConfig) => {
   // Web App Manifest
   router.get("/app.webmanifest", manifestController.get);
 
+  // Client metadata
+  router.get("/id", clientController.get);
+
   // Session
   router.get("/session/login", limit, sessionController.login);
   router.post("/session/login", limit, indieauth.login());
diff --git a/packages/indiekit/test/integration/200-client.js b/packages/indiekit/test/integration/200-client.js
new file mode 100644
index 000000000..952a3fdc5
--- /dev/null
+++ b/packages/indiekit/test/integration/200-client.js
@@ -0,0 +1,24 @@
+import { strict as assert } from "node:assert";
+import { after, describe, it } from "node:test";
+import supertest from "supertest";
+import { testServer } from "@indiekit-test/server";
+
+const server = await testServer();
+const request = supertest.agent(server);
+
+describe("indiekit GET /id", () => {
+  it("Returns client metadata", async () => {
+    const result = await request.get("/id");
+
+    assert.equal(result.status, 200);
+    assert.equal(result.type, "application/json");
+    assert.equal(result.body.client_id.includes("/id"), true);
+    assert.equal(result.body.client_name, "Test configuration");
+    assert.ok(result.body.client_uri);
+    assert.equal(result.body.logo_uri.includes("app-icon-512-any.png"), true);
+  });
+
+  after(() => {
+    server.close(() => process.exit(0));
+  });
+});