diff --git a/modules/connatixBidAdapter.js b/modules/connatixBidAdapter.js
index 0b840db6c26..728d96da067 100644
--- a/modules/connatixBidAdapter.js
+++ b/modules/connatixBidAdapter.js
@@ -9,7 +9,7 @@ import {
   isArray,
   formatQS
 } from '../src/utils.js';
-
+import {getStorageManager} from '../src/storageManager.js';
 import {
   BANNER,
 } from '../src/mediaTypes.js';
@@ -18,6 +18,9 @@ const BIDDER_CODE = 'connatix';
 const AD_URL = 'https://capi.connatix.com/rtb/hba';
 const DEFAULT_MAX_TTL = '3600';
 const DEFAULT_CURRENCY = 'USD';
+const CNX_IDS = 'cnx_ids';
+const CNX_ID_RETENTION_TIME_HOUR = 24 * 30; // 30 days
+export const storage = getStorageManager({ bidderCode: BIDDER_CODE });
 
 /*
  * Get the bid floor value from the bid object, either using the getFloor function or by accessing the 'params.bidfloor' property.
@@ -41,6 +44,21 @@ export function getBidFloor(bid) {
   }
 }
 
+function saveOnAllStorages(name, value, expirationTimeHours) {
+  const date = new Date();
+  date.setTime(date.getTime() + (expirationTimeHours * 60 * 60 * 1000));
+  const expires = `expires=${date.toUTCString()}`;
+  storage.setCookie(name, value, expires);
+  storage.setDataInLocalStorage(name, value);
+}
+
+function readFromAllStorages(name) {
+  const fromCookie = storage.getCookie(name);
+  const fromLocalStorage = storage.getDataFromLocalStorage(name);
+
+  return fromCookie || fromLocalStorage || undefined;
+}
+
 export const spec = {
   code: BIDDER_CODE,
   gvlid: 143,
@@ -94,12 +112,14 @@ export const spec = {
       };
     });
 
+    const cnxIds = readFromAllStorages(CNX_IDS);
     const requestPayload = {
       ortb2: bidderRequest.ortb2,
       gdprConsent: bidderRequest.gdprConsent,
       uspConsent: bidderRequest.uspConsent,
       gppConsent: bidderRequest.gppConsent,
       refererInfo: bidderRequest.refererInfo,
+      userIds: cnxIds,
       bidRequests,
     };
 
@@ -171,6 +191,20 @@ export const spec = {
       params['us_privacy'] = encodeURIComponent(uspConsent);
     }
 
+    window.addEventListener('message', function handler(event) {
+      if (!event.data || !event.origin.includes('connatix')) {
+        return;
+      }
+      this.removeEventListener('message', handler);
+
+      event.stopImmediatePropagation();
+
+      const response = event.data;
+      if (!response.optout && response.eids) {
+        saveOnAllStorages(CNX_IDS, response.eids, CNX_ID_RETENTION_TIME_HOUR);
+      }
+    }, true)
+
     const syncUrl = serverResponses[0].body.UserSyncEndpoint;
     const queryParams = Object.keys(params).length > 0 ? formatQS(params) : '';