diff --git a/modules/.submodules.json b/modules/.submodules.json
index 09063deea40..130e7e8817e 100644
--- a/modules/.submodules.json
+++ b/modules/.submodules.json
@@ -4,7 +4,8 @@
     "id5IdSystem",
     "criteortusIdSystem",
     "parrableIdSystem",
-    "liveIntentIdSystem"
+    "liveIntentIdSystem",
+    "criteoIdSystem"
   ],
   "adpod": [
     "freeWheelAdserverVideo",
diff --git a/modules/criteoIdSystem.js b/modules/criteoIdSystem.js
new file mode 100644
index 00000000000..fe89de5d341
--- /dev/null
+++ b/modules/criteoIdSystem.js
@@ -0,0 +1,132 @@
+/**
+ * This module adds Criteo Real Time User Sync to the User ID module
+ * The {@link module:modules/userId} module is required
+ * @module modules/criteoIdSystem
+ * @requires module:modules/userId
+ */
+
+import * as utils from '../src/utils'
+import * as ajax from '../src/ajax'
+import * as urlLib from '../src/url'
+import { getRefererInfo } from '../src/refererDetection'
+import { submodule } from '../src/hook';
+
+const bididStorageKey = 'cto_bidid';
+const bundleStorageKey = 'cto_bundle';
+const cookieWriteableKey = 'cto_test_cookie';
+const cookiesMaxAge = 13 * 30 * 24 * 60 * 60 * 1000;
+
+const pastDateString = new Date(0).toString();
+const expirationString = new Date(utils.timestamp() + cookiesMaxAge).toString();
+
+function areCookiesWriteable() {
+  utils.setCookie(cookieWriteableKey, '1');
+  const canWrite = utils.getCookie(cookieWriteableKey) === '1';
+  utils.setCookie(cookieWriteableKey, '', pastDateString);
+  return canWrite;
+}
+
+function extractProtocolHost (url, returnOnlyHost = false) {
+  const parsedUrl = urlLib.parse(url)
+  return returnOnlyHost
+    ? `${parsedUrl.hostname}`
+    : `${parsedUrl.protocol}://${parsedUrl.hostname}${parsedUrl.port ? ':' + parsedUrl.port : ''}/`;
+}
+
+function getFromAllStorages(key) {
+  return utils.getCookie(key) || utils.getDataFromLocalStorage(key);
+}
+
+function saveOnAllStorages(key, value) {
+  if (key && value) {
+    utils.setCookie(key, value, expirationString);
+    utils.setDataInLocalStorage(key, value);
+  }
+}
+
+function deleteFromAllStorages(key) {
+  utils.setCookie(key, '', pastDateString);
+  utils.removeDataFromLocalStorage(key);
+}
+
+function getCriteoDataFromAllStorages() {
+  return {
+    bundle: getFromAllStorages(bundleStorageKey),
+    bidId: getFromAllStorages(bididStorageKey),
+  }
+}
+
+function buildCriteoUsersyncUrl(topUrl, domain, bundle, areCookiesWriteable, isPublishertagPresent) {
+  const url = 'https://gum.criteo.com/sid/json?origin=prebid' +
+    `${topUrl ? '&topUrl=' + encodeURIComponent(topUrl) : ''}` +
+    `${domain ? '&domain=' + encodeURIComponent(domain) : ''}` +
+    `${bundle ? '&bundle=' + encodeURIComponent(bundle) : ''}` +
+    `${areCookiesWriteable ? '&cw=1' : ''}` +
+    `${isPublishertagPresent ? '&pbt=1' : ''}`
+
+  return url;
+}
+
+function callCriteoUserSync(parsedCriteoData) {
+  const cw = areCookiesWriteable();
+  const topUrl = extractProtocolHost(getRefererInfo().referer);
+  const domain = extractProtocolHost(document.location.href, true);
+  const isPublishertagPresent = typeof criteo_pubtag !== 'undefined'; // eslint-disable-line camelcase
+
+  const url = buildCriteoUsersyncUrl(
+    topUrl,
+    domain,
+    parsedCriteoData.bundle,
+    cw,
+    isPublishertagPresent
+  );
+
+  ajax.ajaxBuilder()(
+    url,
+    response => {
+      const jsonResponse = JSON.parse(response);
+      if (jsonResponse.bidId) {
+        saveOnAllStorages(bididStorageKey, jsonResponse.bidId);
+      } else {
+        deleteFromAllStorages(bididStorageKey);
+      }
+
+      if (jsonResponse.acwsUrl) {
+        const urlsToCall = typeof jsonResponse.acwsUrl === 'string' ? [jsonResponse.acwsUrl] : jsonResponse.acwsUrl;
+        urlsToCall.forEach(url => utils.triggerPixel(url));
+      } else if (jsonResponse.bundle) {
+        saveOnAllStorages(bundleStorageKey, jsonResponse.bundle);
+      }
+    }
+  );
+}
+
+/** @type {Submodule} */
+export const criteoIdSubmodule = {
+  /**
+   * used to link submodule with config
+   * @type {string}
+   */
+  name: 'criteo',
+  /**
+   * decode the stored id value for passing to bid requests
+   * @function
+   * @returns {{criteoId: string} | undefined}
+   */
+  decode(bidId) {
+    return bidId;
+  },
+  /**
+   * get the Criteo Id from local storages and initiate a new user sync
+   * @function
+   * @returns {{id: {criteoId: string} | undefined}}}
+   */
+  getId() {
+    let localData = getCriteoDataFromAllStorages();
+    callCriteoUserSync(localData);
+
+    return { id: localData.bidId ? { criteoId: localData.bidId } : undefined }
+  }
+};
+
+submodule('userId', criteoIdSubmodule);
diff --git a/test/spec/modules/criteoIdSystem_spec.js b/test/spec/modules/criteoIdSystem_spec.js
new file mode 100644
index 00000000000..44decfd56b6
--- /dev/null
+++ b/test/spec/modules/criteoIdSystem_spec.js
@@ -0,0 +1,135 @@
+import { criteoIdSubmodule } from 'modules/criteoIdSystem';
+import * as utils from 'src/utils';
+import * as ajaxLib from 'src/ajax';
+import * as urlLib from 'src/url';
+
+const pastDateString = new Date(0).toString()
+
+function mockResponse(responseText, fakeResponse = (url, callback) => callback(responseText)) {
+  return function() {
+    return fakeResponse;
+  }
+}
+
+describe('CriteoId module', function () {
+  const cookiesMaxAge = 13 * 30 * 24 * 60 * 60 * 1000;
+
+  const nowTimestamp = new Date().getTime();
+
+  let getCookieStub;
+  let setCookieStub;
+  let getLocalStorageStub;
+  let setLocalStorageStub;
+  let removeFromLocalStorageStub;
+  let timeStampStub;
+  let parseUrlStub;
+  let ajaxBuilderStub;
+  let triggerPixelStub;
+
+  beforeEach(function (done) {
+    getCookieStub = sinon.stub(utils, 'getCookie');
+    setCookieStub = sinon.stub(utils, 'setCookie');
+    getLocalStorageStub = sinon.stub(utils, 'getDataFromLocalStorage');
+    setLocalStorageStub = sinon.stub(utils, 'setDataInLocalStorage');
+    removeFromLocalStorageStub = sinon.stub(utils, 'removeDataFromLocalStorage');
+    timeStampStub = sinon.stub(utils, 'timestamp').returns(nowTimestamp);
+    ajaxBuilderStub = sinon.stub(ajaxLib, 'ajaxBuilder').callsFake(mockResponse('{}'));
+    parseUrlStub = sinon.stub(urlLib, 'parse').returns({protocol: 'https', hostname: 'testdev.com'})
+    triggerPixelStub = sinon.stub(utils, 'triggerPixel');
+    done();
+  });
+
+  afterEach(function () {
+    getCookieStub.restore();
+    setCookieStub.restore();
+    getLocalStorageStub.restore();
+    setLocalStorageStub.restore();
+    removeFromLocalStorageStub.restore();
+    timeStampStub.restore();
+    ajaxBuilderStub.restore();
+    triggerPixelStub.restore();
+    parseUrlStub.restore();
+  });
+
+  const storageTestCases = [
+    { cookie: 'bidId', localStorage: 'bidId2', expected: 'bidId' },
+    { cookie: 'bidId', localStorage: undefined, expected: 'bidId' },
+    { cookie: undefined, localStorage: 'bidId', expected: 'bidId' },
+    { cookie: undefined, localStorage: undefined, expected: undefined },
+  ]
+
+  storageTestCases.forEach(testCase => it('getId() should return the bidId when it exists in local storages', function () {
+    getCookieStub.withArgs('cto_bidid').returns(testCase.cookie);
+    getLocalStorageStub.withArgs('cto_bidid').returns(testCase.localStorage);
+
+    const id = criteoIdSubmodule.getId();
+    expect(id).to.be.deep.equal({id: testCase.expected ? { criteoId: testCase.expected } : undefined});
+  }))
+
+  it('decode() should return the bidId when it exists in local storages', function () {
+    const id = criteoIdSubmodule.decode('testDecode');
+    expect(id).to.equal('testDecode')
+  });
+
+  it('should call user sync url with the right params', function () {
+    getCookieStub.withArgs('cto_test_cookie').returns('1');
+    getCookieStub.withArgs('cto_bundle').returns('bundle');
+    window.criteo_pubtag = {}
+
+    const emptyObj = '{}';
+    let ajaxStub = sinon.stub().callsFake((url, callback) => callback(emptyObj));
+    ajaxBuilderStub.callsFake(mockResponse(undefined, ajaxStub))
+
+    criteoIdSubmodule.getId();
+    const expectedUrl = `https://gum.criteo.com/sid/json?origin=prebid&topUrl=https%3A%2F%2Ftestdev.com%2F&domain=testdev.com&bundle=bundle&cw=1&pbt=1`;
+
+    expect(ajaxStub.calledWith(expectedUrl)).to.be.true;
+
+    window.criteo_pubtag = undefined;
+  });
+
+  const responses = [
+    { bundle: 'bundle', bidId: 'bidId', acwsUrl: 'acwsUrl' },
+    { bundle: 'bundle', bidId: undefined, acwsUrl: 'acwsUrl' },
+    { bundle: 'bundle', bidId: 'bidId', acwsUrl: undefined },
+    { bundle: undefined, bidId: 'bidId', acwsUrl: 'acwsUrl' },
+    { bundle: 'bundle', bidId: undefined, acwsUrl: undefined },
+    { bundle: undefined, bidId: 'bidId', acwsUrl: undefined },
+    { bundle: undefined, bidId: undefined, acwsUrl: 'acwsUrl' },
+    { bundle: undefined, bidId: undefined, acwsUrl: ['acwsUrl', 'acwsUrl2'] },
+    { bundle: undefined, bidId: undefined, acwsUrl: undefined },
+  ]
+
+  responses.forEach(response => describe('test user sync response behavior', function () {
+    const expirationTs = new Date(nowTimestamp + cookiesMaxAge).toString();
+
+    beforeEach(function (done) {
+      const fakeResponse = (url, callback) => {
+        callback(JSON.stringify(response));
+        setTimeout(done, 0);
+      }
+      ajaxBuilderStub.callsFake(mockResponse(undefined, fakeResponse));
+      criteoIdSubmodule.getId();
+    })
+
+    it('should save bidId if it exists', function () {
+      if (response.acwsUrl) {
+        expect(triggerPixelStub.called).to.be.true;
+        expect(setCookieStub.calledWith('cto_bundle')).to.be.false;
+        expect(setLocalStorageStub.calledWith('cto_bundle')).to.be.false;
+      } else if (response.bundle) {
+        expect(setCookieStub.calledWith('cto_bundle', response.bundle, expirationTs)).to.be.true;
+        expect(setLocalStorageStub.calledWith('cto_bundle', response.bundle)).to.be.true;
+        expect(triggerPixelStub.called).to.be.false;
+      }
+
+      if (response.bidId) {
+        expect(setCookieStub.calledWith('cto_bidid', response.bidId, expirationTs)).to.be.true;
+        expect(setLocalStorageStub.calledWith('cto_bidid', response.bidId)).to.be.true;
+      } else {
+        expect(setCookieStub.calledWith('cto_bidid', '', pastDateString)).to.be.true;
+        expect(removeFromLocalStorageStub.calledWith('cto_bidid')).to.be.true;
+      }
+    });
+  }));
+});