> ## Documentation Index
> Fetch the complete documentation index at: https://moengage-sdk-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Proxy Domain - Web

## Introduction

In today’s digital landscape, a significant portion of online users employ ad blockers like [uBlock Origin](https://chromewebstore.google.com/detail/ublock-origin/cjpalhdlnbpafiamejdnhcphjbkeiagm/related?hl=en), [AdGuard](https://adguard.com/en/welcome.html), and [Total Adblock](https://www.totaladblock.com/). These ad blockers are adopted to combat intrusive advertising, enhance browsing speed, and protect online privacy.

However, the prevalent adoption of ad blockers presents a significant obstacle for B2C brands that depend on precise user data. Ad blockers frequently employ domain blacklisting to detect and block communication with domains known for tracking. Consequently, this leads to the collection of incomplete or unreliable data.

To overcome these limitations, MoEngage suggests using **Custom Proxy Domains**. This technical documentation details an integration method that routes SDK traffic through your own subdomain, bypassing blacklist filters while maximizing data fidelity.

## Implementation Guide

<Info>
  **Prerequisite: DNS Delegation**

  Before updating your SDK code, you must delegate a subdomain to MoEngage. Please refer to our [DNS Delegation Help Documentation](https://help.moengage.com/hc/en-us/articles/45199793953300-Custom-Proxy-Sub-Domains) for the step-by-step process on picking a domain and configuring NS records.
</Info>

### Implementation Process

The MoEngage Web SDK uses an internal interceptor and hostname replacement to dynamically rewrite outgoing requests. Instead of reaching out to standard MoEngage endpoints, the SDK prefixes your custom subdomain to all network calls, including API data, scripts, and campaign assets (images).

The process involves:

* Updating the SDK initialization script on your website.
* Updating the Service Worker (`serviceworker.js`) file.
* **Optional:** Implementing the Web Personalization snippet.

## Updating the SDK Initialization

When implementing the initialization code, replace the standard script with the snippet below. You must define your `moeDataCenter`, `moeAppID`, and `customProxyDomain`. This script dynamically constructs the `scriptHost` to ensure the SDK itself is loaded from your proxied CDN.

<CodeGroup>
  ```javascript JavaScript lines wrap theme={"theme":{"light":"github-light","dark":"github-dark"}}
  <script type="text/javascript">
  var moeDataCenter = "{DC}"; // Replace "DC" with the actual Data center value (e.g., dc_1)
  var moeAppID = "{WorkspaceID}"; // Replace with your Workspace ID
  var sdkVersion = "2"; // Use format x (major version)
  var customProxyDomain = "yoursubdomain.yourdomain.com"; // Your configured subdomain hostname
  var scriptHost = "https://cdn." + customProxyDomain; 

  !function(e,n,i,t,a,r,o,d){if(!moeDataCenter||!moeDataCenter.match(/^dc_[0-9]+$/gm))return console.error("Data center has not been passed correctly. Please follow the SDK installation instruction carefully.");var s=e[a]=e[a]||[];if(s.invoked=0,s.initialised>0||s.invoked>0)return console.error("MoEngage Web SDK initialised multiple times. Please integrate the Web SDK only once!"),!1;e.moengage_object=a;var l={},g=function n(i){return function(){for(var n=arguments.length,t=Array(n),a=0;a<n;a++)t[a]=arguments[a];(e.moengage_q=e.moengage_q||[]).push({f:i,a:t})}},u=["track_event","add_user_attribute","add_first_name","add_last_name","add_email","add_mobile","add_user_name","add_gender","add_birthday","destroy_session","add_unique_user_id","update_unique_user_id","moe_events","call_web_push","track","location_type_attribute","identifyUser","getUserIdentities"],m={onsite:["getData","registerCallback","getSelfHandledOSM"]};for(var c in u)l[u[c]]=g(u[c]);for(var v in m)for(var f in m[v])null==l[v]&&(l[v]={}),l[v][m[v][f]]=g(v+"."+m[v][f]);r=n.createElement(i),o=n.getElementsByTagName("head")[0],r.async=1,r.src=t,o.appendChild(r),e.moe=e.moe||function(){return(s.invoked=s.invoked+1,s.invoked>1)?(console.error("MoEngage Web SDK initialised multiple times. Please integrate the Web SDK only once!"),!1):(d=arguments.length<=0?void 0:arguments[0],l)},r.addEventListener("load",function(){if(d)return e[a]=e.moe(d),e[a].initialised=e[a].initialised+1||1,!0}),r.addEventListener("error",function(){return console.error("Moengage Web SDK loading failed."),!1})}(window,document,"script",scriptHost + "/release/"+moeDataCenter+"/versions/"+sdkVersion+"/moe_webSdk.min.latest.js","Moengage");

  Moengage = moe({
    app_id: moeAppID,
    env: 'LIVE',
    logLevel: 0,
    customProxyDomain: customProxyDomain
  });
  </script>
  ```
</CodeGroup>

## Updating the Service Worker (SW)

If you are using Push Notifications or other background features, you must also update the `serviceworker.js` (or your custom service worker file) to include the proxy domain.

<CodeGroup>
  ```javascript Service Worker lines wrap theme={"theme":{"light":"github-light","dark":"github-dark"}}
  // In your serviceworker.js file
  // Replace yoursubdomain.yourdomain.com with your customProxyDomain
  // Replace your_data_center with your actual data center (e.g., dc_1)
  importScripts("[https://cdn.yoursubdomain.yourdomain.com/release/your_data_center/versions/2/serviceworker_cdn.min.latest.js](https://cdn.yoursubdomain.yourdomain.com/release/your_data_center/versions/2/serviceworker_cdn.min.latest.js)");
  ```
</CodeGroup>

## Web Personalization Integration

If your account uses Web Personalization, you must add the following tags to the top of the `<head>` section of your HTML file. This ensures that personalization scripts and campaign assets are pre-fetched and loaded via your custom proxy domain.

<CodeGroup>
  ```html HTML Header lines wrap theme={"theme":{"light":"github-light","dark":"github-dark"}}
  <link rel="preconnect" href="[https://cdn.yoursubdomain.yourdomain.com/](https://cdn.yoursubdomain.yourdomain.com/)" crossorigin />
  <link rel="dns-prefetch" href="[https://cdn.yoursubdomain.yourdomain.com/](https://cdn.yoursubdomain.yourdomain.com/)" />
  <link rel="preconnect" href="[https://sdk-0x.yoursubdomain.yourdomain.com/](https://sdk-0x.yoursubdomain.yourdomain.com/)" crossorigin />
  <link rel="dns-prefetch" href="[https://sdk-0x.yoursubdomain.yourdomain.com/](https://sdk-0x.yoursubdomain.yourdomain.com/)" />
  <script src="[https://cdn.yoursubdomain.yourdomain.com/release/your_data_center/versions/2/moe_webSdk_webp.min.latest.js?app_id=YOUR_WORKSPACE_ID&customProxyDomain=yoursubdomain.yourdomain.com](https://cdn.yoursubdomain.yourdomain.com/release/your_data_center/versions/2/moe_webSdk_webp.min.latest.js?app_id=YOUR_WORKSPACE_ID&customProxyDomain=yoursubdomain.yourdomain.com)"></script>
  ```
</CodeGroup>

## Verifying the Interceptor

Once integrated, the SDK's internal interceptor will automatically map requests as follows:

| Original Endpoint      | Proxied Endpoint                       |
| :--------------------- | :------------------------------------- |
| `sdk-0x.moengage.com`  | `sdk-0x.yoursubdomain.yourdomain.com`  |
| `cdn.moengage.com`     | `cdn.yoursubdomain.yourdomain.com`     |
| `image.moengage.com`   | `image.yoursubdomain.yourdomain.com`   |
| `app-cdn.moengage.com` | `app-cdn.yoursubdomain.yourdomain.com` |

<Tip>
  **Validation Tip**

  Open your browser's Developer Tools (Network Tab) and filter by your custom domain (e.g., "example.com"). Verify that all MoEngage-related traffic is being successfully routed through your subdomain.
</Tip>

For Web SDK integration support, please feel free to reach out to [our support team](https://help.moengage.com/hc/en-us/articles/19708702327572-Raise-a-Support-Ticket-Through-MoEngage-Dashboard).