diff --git a/.github/workflows/publish_prerelease.yml b/.github/workflows/publish_prerelease.yml
index 116cd9b5d..2f7491620 100644
--- a/.github/workflows/publish_prerelease.yml
+++ b/.github/workflows/publish_prerelease.yml
@@ -61,7 +61,7 @@ jobs:
         run: node common/scripts/install-run-rush.js test --verbose
 
       - name: Install API Extractor & Documenter
-        run: npm install -g @microsoft/api-extractor@^7.18.4 @microsoft/api-documenter@^7.13.34
+        run: npm install -g @microsoft/api-extractor@7.18.4 @microsoft/api-documenter@7.13.34
 
       - name: Create API documentation for @snowplow/browser-tracker
         working-directory: ./trackers/browser-tracker
diff --git a/common/changes/@snowplow/browser-plugin-focalmeter/issue-focalmeter_2022-12-22-13-04.json b/common/changes/@snowplow/browser-plugin-focalmeter/issue-focalmeter_2022-12-22-13-04.json
new file mode 100644
index 000000000..325547edf
--- /dev/null
+++ b/common/changes/@snowplow/browser-plugin-focalmeter/issue-focalmeter_2022-12-22-13-04.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@snowplow/browser-plugin-focalmeter",
+      "comment": "Add plugin to send requests with user ID to a Kantar FocalMeter endpoint (#1133)",
+      "type": "none"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-focalmeter"
+}
\ No newline at end of file
diff --git a/common/changes/@snowplow/browser-tracker-core/issue-1124-client_session_2022-12-23-13-19.json b/common/changes/@snowplow/browser-tracker-core/issue-1124-client_session_2022-12-23-13-19.json
new file mode 100644
index 000000000..68088f330
--- /dev/null
+++ b/common/changes/@snowplow/browser-tracker-core/issue-1124-client_session_2022-12-23-13-19.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@snowplow/browser-tracker-core",
+      "comment": "Add client_session context entity if anonymous tracking with session tracking is enabled (#1124)",
+      "type": "none"
+    }
+  ],
+  "packageName": "@snowplow/browser-tracker-core"
+}
\ No newline at end of file
diff --git a/common/config/rush/browser-approved-packages.json b/common/config/rush/browser-approved-packages.json
index 8dbba135f..a80fc2a9b 100644
--- a/common/config/rush/browser-approved-packages.json
+++ b/common/config/rush/browser-approved-packages.json
@@ -130,6 +130,10 @@
       "name": "@snowplow/browser-plugin-youtube-tracking",
       "allowedCategories": [ "trackers" ]
     },
+    {
+      "name": "@snowplow/browser-plugin-focalmeter",
+      "allowedCategories": [ "trackers" ]
+    },
     {
       "name": "@snowplow/browser-tracker",
       "allowedCategories": [ "plugins", "trackers" ]
diff --git a/common/config/rush/pnpm-lock.yaml b/common/config/rush/pnpm-lock.yaml
index c047e77ff..af812adfb 100644
--- a/common/config/rush/pnpm-lock.yaml
+++ b/common/config/rush/pnpm-lock.yaml
@@ -572,6 +572,55 @@ importers:
       ts-jest: 27.1.3_60149d457e34ffba7d4e845dde6a1263
       typescript: 4.6.2
 
+  ../../plugins/browser-plugin-focalmeter:
+    specifiers:
+      '@ampproject/rollup-plugin-closure-compiler': ~0.27.0
+      '@rollup/plugin-commonjs': ~21.0.2
+      '@rollup/plugin-node-resolve': ~13.1.3
+      '@snowplow/browser-tracker-core': workspace:*
+      '@snowplow/tracker-core': workspace:*
+      '@types/jest': ~27.4.1
+      '@types/jsdom': ~16.2.14
+      '@typescript-eslint/eslint-plugin': ~5.15.0
+      '@typescript-eslint/parser': ~5.15.0
+      eslint: ~8.11.0
+      jest: ~27.5.1
+      jest-environment-jsdom: ~27.5.1
+      jest-environment-jsdom-global: ~3.0.0
+      jest-standard-reporter: ~2.0.0
+      rollup: ~2.70.1
+      rollup-plugin-cleanup: ~3.2.1
+      rollup-plugin-license: ~2.6.1
+      rollup-plugin-terser: ~7.0.2
+      rollup-plugin-ts: ~2.0.5
+      ts-jest: ~27.1.3
+      tslib: ^2.3.1
+      typescript: ~4.6.2
+    dependencies:
+      '@snowplow/browser-tracker-core': link:../../libraries/browser-tracker-core
+      '@snowplow/tracker-core': link:../../libraries/tracker-core
+      tslib: 2.3.1
+    devDependencies:
+      '@ampproject/rollup-plugin-closure-compiler': 0.27.0_rollup@2.70.1
+      '@rollup/plugin-commonjs': 21.0.2_rollup@2.70.1
+      '@rollup/plugin-node-resolve': 13.1.3_rollup@2.70.1
+      '@types/jest': 27.4.1
+      '@types/jsdom': 16.2.14
+      '@typescript-eslint/eslint-plugin': 5.15.0_f2c49ce7d0e93ebcfdb4b7d25b131b28
+      '@typescript-eslint/parser': 5.15.0_eslint@8.11.0+typescript@4.6.2
+      eslint: 8.11.0
+      jest: 27.5.1
+      jest-environment-jsdom: 27.5.1
+      jest-environment-jsdom-global: 3.0.0_jest-environment-jsdom@27.5.1
+      jest-standard-reporter: 2.0.0
+      rollup: 2.70.1
+      rollup-plugin-cleanup: 3.2.1_rollup@2.70.1
+      rollup-plugin-license: 2.6.1_rollup@2.70.1
+      rollup-plugin-terser: 7.0.2_rollup@2.70.1
+      rollup-plugin-ts: 2.0.5_rollup@2.70.1+typescript@4.6.2
+      ts-jest: 27.1.3_60149d457e34ffba7d4e845dde6a1263
+      typescript: 4.6.2
+
   ../../plugins/browser-plugin-form-tracking:
     specifiers:
       '@ampproject/rollup-plugin-closure-compiler': ~0.27.0
diff --git a/common/config/rush/repo-state.json b/common/config/rush/repo-state.json
index 3c7f1fddd..fc675a41f 100644
--- a/common/config/rush/repo-state.json
+++ b/common/config/rush/repo-state.json
@@ -1,5 +1,5 @@
 // DO NOT MODIFY THIS FILE MANUALLY BUT DO COMMIT IT. It is generated and used by Rush.
 {
-  "pnpmShrinkwrapHash": "a89befd25d9043396ee1a3dda2def22a80582f46",
+  "pnpmShrinkwrapHash": "f6c3c1da60e38fc2db1587dd57a4b39e2ff21caf",
   "preferredVersionsHash": "bf21a9e8fbc5a3846fb05b4fa0859e0917b2202f"
 }
diff --git a/common/config/rush/version-policies.json b/common/config/rush/version-policies.json
index 9ded67980..1b713a40f 100644
--- a/common/config/rush/version-policies.json
+++ b/common/config/rush/version-policies.json
@@ -33,7 +33,7 @@
      * in the current branch.  When bumping versions, Rush uses this to determine the next version.
      * (The "version" field in package.json is NOT considered.)
      */
-    "version": "3.8.0",
+    "version": "3.9.0-beta.0",
   
     /**
      * (Required) The type of bump that will be performed when publishing the next release.
@@ -42,6 +42,6 @@
      *
      * Valid values are: "prerelease", "release", "minor", "patch", "major"
      */
-    "nextBump": "minor"
+    "nextBump": "prerelease"
   }
 ]
diff --git a/libraries/browser-tracker-core/src/tracker/id_cookie.ts b/libraries/browser-tracker-core/src/tracker/id_cookie.ts
index 6277d8f50..c350f8f5d 100644
--- a/libraries/browser-tracker-core/src/tracker/id_cookie.ts
+++ b/libraries/browser-tracker-core/src/tracker/id_cookie.ts
@@ -300,14 +300,20 @@ export function serializeIdCookie(idCookie: ParsedIdCookie) {
  * @param configStateStorageStrategy Cookie storage strategy
  * @returns Client session context entity
  */
-export function clientSessionFromIdCookie(idCookie: ParsedIdCookie, configStateStorageStrategy: string) {
+export function clientSessionFromIdCookie(
+  idCookie: ParsedIdCookie,
+  configStateStorageStrategy: string,
+  configAnonymousTracking: boolean
+) {
   const firstEventTsInMs = idCookie[firstEventTsInMsIndex];
   const clientSession: ClientSession = {
-    userId: idCookie[domainUserIdIndex],
+    userId: configAnonymousTracking
+      ? '00000000-0000-0000-0000-000000000000' // TODO: use uuid.NIL when we upgrade to uuid v8.3
+      : idCookie[domainUserIdIndex],
     sessionId: idCookie[sessionIdIndex],
     eventIndex: idCookie[eventIndexIndex],
     sessionIndex: idCookie[visitCountIndex],
-    previousSessionId: idCookie[previousSessionIdIndex] || null,
+    previousSessionId: configAnonymousTracking ? null : idCookie[previousSessionIdIndex] || null,
     storageMechanism: configStateStorageStrategy == 'localStorage' ? 'LOCAL_STORAGE' : 'COOKIE_1',
     firstEventId: idCookie[firstEventIdIndex] || null,
     firstEventTimestamp: firstEventTsInMs ? new Date(firstEventTsInMs).toISOString() : null,
diff --git a/libraries/browser-tracker-core/src/tracker/index.ts b/libraries/browser-tracker-core/src/tracker/index.ts
index b2bcb4362..1952485fd 100755
--- a/libraries/browser-tracker-core/src/tracker/index.ts
+++ b/libraries/browser-tracker-core/src/tracker/index.ts
@@ -787,8 +787,11 @@ export function Tracker(
           // Add the page URL last as it may take us over the IE limit (and we don't always need it)
           payloadBuilder.add('url', purify(configCustomUrl || locationHrefAlias));
 
-          if (configSessionContext && !configAnonymousSessionTracking && !configAnonymousTracking) {
-            addSessionContextToPayload(payloadBuilder, clientSessionFromIdCookie(idCookie, configStateStorageStrategy));
+          if (configSessionContext && (!configAnonymousTracking || configAnonymousSessionTracking)) {
+            addSessionContextToPayload(
+              payloadBuilder,
+              clientSessionFromIdCookie(idCookie, configStateStorageStrategy, configAnonymousTracking)
+            );
           }
 
           // Update cookies
diff --git a/libraries/browser-tracker-core/test/id_cookie.test.ts b/libraries/browser-tracker-core/test/id_cookie.test.ts
index cca0fcd09..aadbea178 100644
--- a/libraries/browser-tracker-core/test/id_cookie.test.ts
+++ b/libraries/browser-tracker-core/test/id_cookie.test.ts
@@ -262,7 +262,7 @@ describe('serializeIdCookie', () => {
 describe('clientSessionFromIdCookie', () => {
   it('Correctly fills out the properties', () => {
     let idCookie = parseIdCookie('def.1653632272.10.1653632282.1653632262.ses.previous.fid.1653638673483.9', '', '', 0);
-    let clientSession = clientSessionFromIdCookie(idCookie, 'cookieAndLocalStorage');
+    let clientSession = clientSessionFromIdCookie(idCookie, 'cookieAndLocalStorage', false);
 
     expect(clientSession.userId).toBe('def');
     expect(clientSession.sessionId).toBe('ses');
@@ -273,4 +273,18 @@ describe('clientSessionFromIdCookie', () => {
     expect(clientSession.firstEventId).toBe('fid');
     expect(clientSession.firstEventTimestamp).toBe('2022-05-27T08:04:33.483Z');
   });
+
+  it('Anonymises userId and previousSessionId when anonymous tracking', () => {
+    let idCookie = parseIdCookie('def.1653632272.10.1653632282.1653632262.ses.previous.fid.1653638673483.9', '', '', 0);
+    let clientSession = clientSessionFromIdCookie(idCookie, 'cookieAndLocalStorage', true);
+
+    expect(clientSession.userId).toBe('00000000-0000-0000-0000-000000000000');
+    expect(clientSession.sessionId).toBe('ses');
+    expect(clientSession.previousSessionId).toBeNull;
+    expect(clientSession.eventIndex).toBe(9);
+    expect(clientSession.sessionIndex).toBe(10);
+    expect(clientSession.storageMechanism).toBe('COOKIE_1');
+    expect(clientSession.firstEventId).toBe('fid');
+    expect(clientSession.firstEventTimestamp).toBe('2022-05-27T08:04:33.483Z');
+  });
 });
diff --git a/libraries/browser-tracker-core/test/tracker/session_data.test.ts b/libraries/browser-tracker-core/test/tracker/session_data.test.ts
index d000b30a2..c64a991fd 100644
--- a/libraries/browser-tracker-core/test/tracker/session_data.test.ts
+++ b/libraries/browser-tracker-core/test/tracker/session_data.test.ts
@@ -28,6 +28,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+import { TrackerConfiguration } from '../../dist/index.module';
 import { addTracker, SharedState } from '../../src';
 import { createTestIdCookie, createTestSessionIdCookie } from '../helpers';
 
@@ -54,7 +55,7 @@ describe('Tracker API: ', () => {
   });
 
   it('Sets initial domain session index on first session', () => {
-    const tracker = addTracker('sp1', 'sp1', '', '', new SharedState());
+    const tracker = createTracker();
 
     expect(tracker?.getDomainSessionIndex()).toEqual(1);
   });
@@ -62,7 +63,7 @@ describe('Tracker API: ', () => {
   it('Sets correct domain session index on new session', () => {
     const initialSessionIndex = 1;
     document.cookie = createTestIdCookie({ visitCount: initialSessionIndex });
-    const tracker = addTracker('sp2', 'sp2', '', '', new SharedState());
+    const tracker = createTracker();
 
     expect(tracker?.getDomainSessionIndex()).toEqual(initialSessionIndex + 1);
   });
@@ -70,7 +71,7 @@ describe('Tracker API: ', () => {
   it('Sets correct domain session index on existing session', () => {
     const initialSessionIndex = 2;
     document.cookie = createTestIdCookie({ visitCount: initialSessionIndex }) + ' ' + createTestSessionIdCookie();
-    const tracker = addTracker('sp3', 'sp3', '', '', new SharedState());
+    const tracker = createTracker();
 
     expect(tracker?.getDomainSessionIndex()).toEqual(initialSessionIndex);
   });
@@ -78,7 +79,7 @@ describe('Tracker API: ', () => {
   it('Sets correct domain session index (1) after clearUserData() on existing session', () => {
     const initialSessionIndex = 2;
     document.cookie = createTestIdCookie({ visitCount: initialSessionIndex }) + ' ' + createTestSessionIdCookie();
-    const tracker = addTracker('sp4', 'sp4', '', '', new SharedState());
+    const tracker = createTracker();
     expect(tracker?.getDomainSessionIndex()).toEqual(initialSessionIndex);
 
     tracker?.clearUserData();
@@ -86,13 +87,13 @@ describe('Tracker API: ', () => {
   });
 
   it('Sets correct domain session index anonymous track', () => {
-    const tracker = addTracker('sp5', 'sp5', '', '', new SharedState(), { anonymousTracking: true });
+    const tracker = createTracker({ anonymousTracking: true });
     expect(tracker?.getDomainSessionIndex()).toEqual(1);
   });
 
   it('Retains correct domain session index on opt-out cookie present', () => {
     const optOutCookieName = 'optOut';
-    const tracker = addTracker('sp6', 'sp6', '', '', new SharedState());
+    const tracker = createTracker();
     tracker?.setOptOutCookie(optOutCookieName);
     document.cookie = `${optOutCookieName}=1;`;
 
@@ -102,10 +103,73 @@ describe('Tracker API: ', () => {
 
   it('Sets correct domain session index after session expiration', () => {
     // Session timeout is in seconds
-    const tracker = addTracker('sp7', 'sp7', '', '', new SharedState(), { sessionCookieTimeout: 1 });
+    const tracker = createTracker({ sessionCookieTimeout: 1 });
     // Advance timer by more than one second
     jest.advanceTimersByTime(1001);
     tracker?.trackPageView({ title: 'my page' });
     expect(tracker?.getDomainSessionIndex()).toEqual(2);
   });
+
+  it('Adds the client session context entity when enabled', (done) => {
+    const tracker = createTracker({
+      contexts: { session: true },
+      encodeBase64: false,
+      plugins: [
+        {
+          afterTrack: (payload) => {
+            let context = payload.co as string;
+            expect(context).toContain('client_session');
+            done();
+          },
+        },
+      ],
+    });
+
+    tracker?.trackPageView();
+  });
+
+  it('Adds the client session context entity when anonymous session tracking', (done) => {
+    const tracker = createTracker({
+      contexts: { session: true },
+      encodeBase64: false,
+      anonymousTracking: { withSessionTracking: true },
+      plugins: [
+        {
+          afterTrack: (payload) => {
+            let context = payload.co as string;
+            expect(context).toContain('client_session');
+            expect(context).toContain('"userId":"00000000-0000-0000-0000-000000000000"');
+            expect(context).toContain('"previousSessionId":null');
+            done();
+          },
+        },
+      ],
+    });
+
+    tracker?.trackPageView();
+  });
+
+  it("Doesn't add the client session context entity when anonymous tracking without session tracking", (done) => {
+    const tracker = createTracker({
+      contexts: { session: true },
+      encodeBase64: false,
+      anonymousTracking: true,
+      plugins: [
+        {
+          afterTrack: (payload) => {
+            let context = payload.co as string;
+            expect(context).not.toContain('client_session');
+            done();
+          },
+        },
+      ],
+    });
+
+    tracker?.trackPageView();
+  });
 });
+
+function createTracker(configuration?: TrackerConfiguration) {
+  let id = 'sp-' + Math.random();
+  return addTracker(id, id, '', '', new SharedState(), configuration);
+}
diff --git a/plugins/browser-plugin-focalmeter/CHANGELOG.json b/plugins/browser-plugin-focalmeter/CHANGELOG.json
new file mode 100644
index 000000000..7f74dc674
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/CHANGELOG.json
@@ -0,0 +1,5 @@
+{
+  "name": "@snowplow/browser-plugin-focalmeter",
+  "entries": [
+  ]
+}
diff --git a/plugins/browser-plugin-focalmeter/LICENSE b/plugins/browser-plugin-focalmeter/LICENSE
new file mode 100644
index 000000000..76f1946ea
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/LICENSE
@@ -0,0 +1,29 @@
+BSD 3-Clause License
+
+Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/plugins/browser-plugin-focalmeter/README.md b/plugins/browser-plugin-focalmeter/README.md
new file mode 100644
index 000000000..668656a21
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/README.md
@@ -0,0 +1,56 @@
+# Snowplow FocalMeter Integration
+
+[![npm version][npm-image]][npm-url]
+[![License][license-image]](LICENSE)
+
+Browser Plugin to be used with `@snowplow/browser-tracker`.
+
+Adds integration with the Kantar FocalMeter to your Snowplow tracking.
+The plugin sends requests with the domain user ID to a Kantar endpoint used with the FocalMeter system.
+A request is made when the first event with a new user ID is tracked.
+
+## Maintainer quick start
+
+Part of the Snowplow JavaScript Tracker monorepo.  
+Build with [Node.js](https://nodejs.org/en/) (14 or 16) and [Rush](https://rushjs.io/).
+
+### Setup repository
+
+```bash
+npm install -g @microsoft/rush 
+git clone https://github.com/snowplow/snowplow-javascript-tracker.git
+rush update
+```
+
+## Package Installation
+
+With npm:
+
+```bash
+npm install @snowplow/browser-plugin-focalmeter
+```
+
+## Usage
+
+Initialize your tracker with the FocalMeterPlugin:
+
+```js
+import { newTracker } from '@snowplow/browser-tracker';
+import { FocalMeterPlugin } from '@snowplow/browser-plugin-focalmeter';
+
+newTracker('sp1', '{{collector}}', { plugins: [ FocalMeterPlugin() ] }); // Also stores reference at module level
+```
+
+## Copyright and license
+
+Licensed and distributed under the [BSD 3-Clause License](LICENSE) ([An OSI Approved License][osi]).
+
+Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang.
+
+All rights reserved.
+
+[npm-url]: https://www.npmjs.com/package/@snowplow/browser-plugin-focalmeter
+[npm-image]: https://img.shields.io/npm/v/@snowplow/browser-plugin-focalmeter
+[docs]: https://docs.snowplowanalytics.com/docs/collecting-data/collecting-from-own-applications/javascript-tracker/
+[osi]: https://opensource.org/licenses/BSD-3-Clause
+[license-image]: https://img.shields.io/npm/l/@snowplow/browser-plugin-focalmeter
diff --git a/plugins/browser-plugin-focalmeter/jest.config.js b/plugins/browser-plugin-focalmeter/jest.config.js
new file mode 100644
index 000000000..bd3ea4e2a
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/jest.config.js
@@ -0,0 +1,5 @@
+module.exports = {
+  preset: 'ts-jest',
+  reporters: ['jest-standard-reporter'],
+  testEnvironment: 'jest-environment-jsdom-global',
+};
diff --git a/plugins/browser-plugin-focalmeter/package.json b/plugins/browser-plugin-focalmeter/package.json
new file mode 100644
index 000000000..67153b30a
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/package.json
@@ -0,0 +1,53 @@
+{
+  "name": "@snowplow/browser-plugin-focalmeter",
+  "version": "3.8.0",
+  "description": "Kantar FocalMeter integration for Snowplow",
+  "homepage": "http://bit.ly/sp-js",
+  "bugs": "https://github.com/snowplow/snowplow-javascript-tracker/issues",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/snowplow/snowplow-javascript-tracker.git"
+  },
+  "license": "BSD-3-Clause",
+  "author": "Matus Tomlein",
+  "sideEffects": false,
+  "main": "./dist/index.umd.js",
+  "module": "./dist/index.module.js",
+  "types": "./dist/index.module.d.ts",
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "build": "rollup -c --silent --failAfterWarnings",
+    "test": "jest"
+  },
+  "dependencies": {
+    "@snowplow/browser-tracker-core": "workspace:*",
+    "@snowplow/tracker-core": "workspace:*",
+    "tslib": "^2.3.1"
+  },
+  "devDependencies": {
+    "@ampproject/rollup-plugin-closure-compiler": "~0.27.0",
+    "@rollup/plugin-commonjs": "~21.0.2",
+    "@rollup/plugin-node-resolve": "~13.1.3",
+    "@types/jest": "~27.4.1",
+    "@types/jsdom": "~16.2.14",
+    "@typescript-eslint/eslint-plugin": "~5.15.0",
+    "@typescript-eslint/parser": "~5.15.0",
+    "eslint": "~8.11.0",
+    "jest": "~27.5.1",
+    "jest-environment-jsdom": "~27.5.1",
+    "jest-environment-jsdom-global": "~3.0.0",
+    "jest-standard-reporter": "~2.0.0",
+    "rollup": "~2.70.1",
+    "rollup-plugin-cleanup": "~3.2.1",
+    "rollup-plugin-license": "~2.6.1",
+    "rollup-plugin-terser": "~7.0.2",
+    "rollup-plugin-ts": "~2.0.5",
+    "ts-jest": "~27.1.3",
+    "typescript": "~4.6.2"
+  },
+  "peerDependencies": {
+    "@snowplow/browser-tracker": "~3.8.0"
+  }
+}
diff --git a/plugins/browser-plugin-focalmeter/rollup.config.js b/plugins/browser-plugin-focalmeter/rollup.config.js
new file mode 100644
index 000000000..1c024021b
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/rollup.config.js
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import { nodeResolve } from '@rollup/plugin-node-resolve';
+import commonjs from '@rollup/plugin-commonjs';
+import ts from 'rollup-plugin-ts'; // Prefered over @rollup/plugin-typescript as it bundles .d.ts files
+import { banner } from '../../banner';
+import compiler from '@ampproject/rollup-plugin-closure-compiler';
+import { terser } from 'rollup-plugin-terser';
+import cleanup from 'rollup-plugin-cleanup';
+import pkg from './package.json';
+import { builtinModules } from 'module';
+
+const umdPlugins = [nodeResolve({ browser: true }), commonjs(), ts()];
+const umdName = 'snowplowFocalMeter';
+
+export default [
+  // CommonJS (for Node) and ES module (for bundlers) build.
+  {
+    input: './src/index.ts',
+    plugins: [...umdPlugins, banner()],
+    treeshake: { moduleSideEffects: ['sha1'] },
+    output: [{ file: pkg.main, format: 'umd', sourcemap: true, name: umdName }],
+  },
+  {
+    input: './src/index.ts',
+    plugins: [...umdPlugins, compiler(), terser(), cleanup({ comments: 'none' }), banner()],
+    treeshake: { moduleSideEffects: ['sha1'] },
+    output: [{ file: pkg.main.replace('.js', '.min.js'), format: 'umd', sourcemap: true, name: umdName }],
+  },
+  {
+    input: './src/index.ts',
+    external: [...builtinModules, ...Object.keys(pkg.dependencies), ...Object.keys(pkg.devDependencies)],
+    plugins: [
+      ts(), // so Rollup can convert TypeScript to JavaScript
+      banner(),
+    ],
+    output: [{ file: pkg.module, format: 'es', sourcemap: true }],
+  },
+];
diff --git a/plugins/browser-plugin-focalmeter/src/index.ts b/plugins/browser-plugin-focalmeter/src/index.ts
new file mode 100644
index 000000000..72841b010
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/src/index.ts
@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import {
+  attemptGetLocalStorage,
+  BrowserPlugin,
+  hasLocalStorage,
+  BrowserTracker,
+  attemptWriteLocalStorage,
+} from '@snowplow/browser-tracker-core';
+import { Logger, Payload } from '@snowplow/tracker-core';
+
+/** FocalMeter plugin configuration */
+export interface FocalMeterConfiguration {
+  /** URL of the Kantar endpoint to send the requests to (including protocol) */
+  kantarEndpoint: string;
+  /** Whether to store information about the last submitted user ID in local storage to prevent sending it again on next load (defaults not to use local storage) */
+  useLocalStorage?: boolean;
+}
+
+const _trackers: Record<string, BrowserTracker> = {};
+const _configurations: Record<string, FocalMeterConfiguration> = {};
+
+/**
+ * The FocalMeter Plugin
+ *
+ * The plugin sends requests with the domain user ID to a Kantar endpoint used with the FocalMeter system.
+ * A request is made when the first event with a new user ID is tracked.
+ *
+ * Call `enableFocalMeterIntegration()` to enable the integration with given configuration.
+ */
+export function FocalMeterPlugin(): BrowserPlugin {
+  let LOG: Logger;
+  let lastUserId: string | undefined | null;
+  let trackerId: string;
+
+  return {
+    activateBrowserPlugin: (tracker: BrowserTracker) => {
+      trackerId = tracker.id;
+      _trackers[tracker.id] = tracker;
+    },
+
+    logger: (logger: Logger) => {
+      LOG = logger;
+    },
+
+    afterTrack: (payload: Payload) => {
+      if (!_configurations[trackerId]) {
+        LOG.error('FocalMeter integration not enabled');
+        return;
+      }
+
+      let newUserId = payload['duid'] as string;
+      let { kantarEndpoint, useLocalStorage } = _configurations[trackerId];
+
+      if (!lastUserId && useLocalStorage && hasLocalStorage()) {
+        let key = getLocalStorageKey(trackerId);
+        lastUserId = attemptGetLocalStorage(key);
+      }
+
+      if (newUserId && newUserId != lastUserId) {
+        lastUserId = newUserId;
+
+        sendRequest(kantarEndpoint, newUserId, LOG, () => {
+          // only write in local storage if the request succeeded
+          if (useLocalStorage && hasLocalStorage()) {
+            let key = getLocalStorageKey(trackerId);
+            attemptWriteLocalStorage(key, newUserId);
+          }
+        });
+      }
+    },
+  };
+}
+
+/**
+ * Enables the integration with Kantar FocalMeter.
+ *
+ * @param configuration - Configuration with the URL endpoint to send requests to
+ * @param trackers - The tracker identifiers which should have the context enabled
+ */
+export function enableFocalMeterIntegration(
+  configuration: FocalMeterConfiguration,
+  trackers: Array<string> = Object.keys(_trackers)
+): void {
+  for (const id of trackers) {
+    if (_trackers[id]) {
+      _configurations[id] = configuration;
+    }
+  }
+}
+
+function getLocalStorageKey(trackerId: string): string {
+  return `sp-fclmtr-${trackerId}`;
+}
+
+function sendRequest(url: string, userId: string, LOG: Logger, successCallback: () => void): void {
+  const xhr = new XMLHttpRequest();
+  xhr.open('GET', getKantarURL(url, userId));
+  xhr.timeout = 5000;
+
+  xhr.onreadystatechange = function () {
+    if (xhr.readyState === 4 && xhr.status >= 200) {
+      if (xhr.status < 300) {
+        successCallback();
+        LOG.debug(`ID sent to Kantar: ${userId}`);
+      } else {
+        LOG.error(`Kantar request failed: ${xhr.status}: ${xhr.statusText}`);
+      }
+    }
+  };
+
+  xhr.send();
+}
+
+function getKantarURL(url: string, userId: string): string {
+  let query: Record<string, string> = {
+    vendor: 'snowplow',
+    cs_fpid: userId,
+    c12: 'not_set',
+  };
+  return (
+    url +
+    '?' +
+    Object.keys(query)
+      .map((key) => key + '=' + query[key])
+      .join('&')
+  );
+}
diff --git a/plugins/browser-plugin-focalmeter/test/request.test.ts b/plugins/browser-plugin-focalmeter/test/request.test.ts
new file mode 100644
index 000000000..6c609e67b
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/test/request.test.ts
@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import { addTracker, SharedState } from '@snowplow/browser-tracker-core';
+import { enableFocalMeterIntegration, FocalMeterPlugin } from '../src';
+
+describe('AdTrackingPlugin', () => {
+  // Mock XHR network requests
+  let xhrMock: Partial<XMLHttpRequest>;
+  let xhrOpenMock: jest.Mock;
+  let queuedStateChangeCallbacks: any[] = [];
+  let domain = 'https://kantar.com';
+
+  beforeEach(() => {
+    xhrOpenMock = jest.fn();
+    xhrMock = {
+      open: xhrOpenMock,
+      send: jest.fn(),
+      setRequestHeader: jest.fn(),
+      withCredentials: true,
+      status: 200,
+      response: '',
+      readyState: 4,
+    };
+
+    Object.defineProperty(xhrMock, 'onreadystatechange', {
+      set: (val) => {
+        queuedStateChangeCallbacks.push(val);
+      },
+    });
+
+    jest.spyOn(window, 'XMLHttpRequest').mockImplementation(() => xhrMock as XMLHttpRequest);
+  });
+
+  it('makes a request to Kantar endpoint with user ID', async () => {
+    let tracker = createTrackerWithPlugin();
+    enableFocalMeterIntegration({ kantarEndpoint: domain });
+
+    tracker?.trackPageView();
+    let userId = tracker?.getDomainUserId();
+
+    await checkMock(() => {
+      expect(xhrOpenMock).toHaveBeenCalledTimes(2);
+      expect(xhrOpenMock).toHaveBeenLastCalledWith('GET', `${domain}?vendor=snowplow&cs_fpid=${userId}&c12=not_set`);
+    });
+  });
+
+  it('makes a request to Kantar endpoint when user ID changes', async () => {
+    let tracker = createTrackerWithPlugin();
+    enableFocalMeterIntegration({ kantarEndpoint: domain });
+
+    // Doesn't make a request if anonymous tracking
+    tracker?.enableAnonymousTracking();
+    tracker?.trackPageView();
+    await checkMock(() => {
+      expect(xhrOpenMock).toHaveBeenCalledTimes(1);
+    });
+
+    // Makes a request when disabling anonymous tracking
+    tracker?.disableAnonymousTracking();
+    tracker?.trackPageView();
+    let userId = tracker?.getDomainUserId();
+    await checkMock(() => {
+      expect(xhrOpenMock).toHaveBeenCalledTimes(2);
+      expect(xhrOpenMock).toHaveBeenLastCalledWith('GET', `${domain}?vendor=snowplow&cs_fpid=${userId}&c12=not_set`);
+    });
+
+    // Doesn't make another request since user ID didn't change
+    tracker?.trackPageView();
+    await checkMock(() => {
+      expect(xhrOpenMock).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  it('can work with multiple trackers', async () => {
+    let tracker1 = createTrackerWithPlugin();
+    let tracker2 = createTrackerWithPlugin();
+
+    enableFocalMeterIntegration(
+      {
+        kantarEndpoint: domain,
+      },
+      [tracker1!.namespace, tracker2!.namespace]
+    );
+
+    // Makes requests for both trackers
+    tracker1?.trackPageView();
+    await checkMock(() => expect(xhrOpenMock).toHaveBeenCalledTimes(2));
+    tracker2?.trackPageView();
+    await checkMock(() => expect(xhrOpenMock).toHaveBeenCalledTimes(2));
+
+    // Doesn't make any more requests for the trackers
+    tracker1?.trackPageView();
+    await checkMock(() => expect(xhrOpenMock).toHaveBeenCalledTimes(1));
+    tracker2?.trackPageView();
+    await checkMock(() => expect(xhrOpenMock).toHaveBeenCalledTimes(1));
+  });
+
+  function createTrackerWithPlugin(id: string | undefined = undefined) {
+    const state = new SharedState();
+    id ??= 'sp-' + Math.random();
+
+    return addTracker(id, id, 'js-3.0.0', '', state, {
+      stateStorageStrategy: 'cookie',
+      encodeBase64: false,
+      plugins: [FocalMeterPlugin()],
+    });
+  }
+
+  function checkMock(callback: () => void) {
+    return new Promise((resolve) => {
+      setTimeout(() => {
+        callback();
+        queuedStateChangeCallbacks.forEach((callback) => callback());
+        queuedStateChangeCallbacks = [];
+        xhrOpenMock.mockReset();
+        resolve(true);
+      }, 100);
+    });
+  }
+});
diff --git a/plugins/browser-plugin-focalmeter/tsconfig.json b/plugins/browser-plugin-focalmeter/tsconfig.json
new file mode 100644
index 000000000..4082f16a5
--- /dev/null
+++ b/plugins/browser-plugin-focalmeter/tsconfig.json
@@ -0,0 +1,3 @@
+{
+  "extends": "../../tsconfig.json"
+}
diff --git a/rush.json b/rush.json
index 9dccb37aa..2959be589 100644
--- a/rush.json
+++ b/rush.json
@@ -541,6 +541,12 @@
       "projectFolder": "plugins/browser-plugin-enhanced-consent",
       "reviewCategory": "plugins",
       "versionPolicyName": "tracker"
+    },
+    {
+      "packageName": "@snowplow/browser-plugin-focalmeter",
+      "projectFolder": "plugins/browser-plugin-focalmeter",
+      "reviewCategory": "plugins",
+      "versionPolicyName": "tracker"
     }
   ]
 }