Merchant Center Proxy Router

Learn about the Merchant Center Proxy Router and how it works with Custom Applications.

This page applies only to Custom Applications.

When you use the Merchant Center, you can switch between the built-in applications and the externally developed applications available to your Project.

The URL of the Merchant Center always uses the same origin and only differs in the URI, depending on the Project and application.

For example:


This way, it looks like you're using a single web application, even though there are multiple applications underneath.

Server-side routing

When a user accesses the Merchant Center through the browser, the request to render the page goes through a server component called Merchant Center Proxy Router.

This server is primarily responsible for matching the incoming request to the appropriate Custom Application using the entryPointUriPath (the identifier of the Custom Application). The request is then forwarded to the actual URL location of the Custom Application, which responds with the index.html file.

A Custom Application is a single-page application that uses client-side routing. This means you must configure your hosting provider to rewrite all requests to serve the index.html file. Conceptually it would look something like this: /* --> /index.html.

To learn more, see Forwarding requests.

Based on the above diagram, the request goes through the following steps:

  1. User accesses the Merchant Center at the following path /my-project/my-app.
  2. The request goes through the Merchant Center Proxy Router, which successfully matches the my-app identifier to the my-project Project.
  3. The configuration for the Custom Application my-app is loaded.
  4. The request is forwarded to the URL of the server hosting the Custom Application.
  5. The server hosting the Custom Application responds with the index.html file.
  6. The Custom Application my-app is rendered in the browser.

Forwarding requests

When the Merchant Center Proxy Router matches a request to a Custom Application, it forwards the original request URI to the Custom Application's configured URL.

# TO

The <app-url> is the Custom Application production URL.

Therefore, the hosting server of the Custom Application must configure URL rewrite rules to handle all requests and serve the index.html file.

For example, given the following data:

  • Application production URL:
  • Application entryPointUriPath: custom-channels

When the user accesses the application in the Merchant Center at https://mc.<cloud-region>, the Merchant Center Proxy Router forwards the request to the following URL

Similarly, any of the following example URLs returns the index.html file:

Configuring rewrite rules is specific to each hosting provider. For more information on how to configure rewrite rules, see Deployment Examples.

Client-side routing

After the browser finishes rendering the index.html file, the Custom Application uses client-side routing to handle the URI location path.

Each Custom Application has a built-in router and a default route configured to match the path /:projectKey/:entryPointUriPath. The value of the entryPointUriPath is defined in the Custom Application config file and exposed via the runtime environment.

Hence, the runtime value of the entryPointUriPath must match the value defined in the Custom Application configuration in the Merchant Center.

For example, if the entryPointUriPath is custom-channels and the user accesses the URL /my-project/custom-channels, the Custom Application renders correctly because the route matches.

// custom-channels
// custom-channels

Page reloading behavior

Each Custom Application defines its routes. However, there might be links to other applications that the Custom Application routes won't match. The same applies when a user clicks on an item in the Merchant Center main menu.

When no route matches the new URI path, the Custom Application forces a full page reload. At this point, the request goes through the Merchant Center Proxy Router, letting the server-side router handle the matching of the route. In most cases, this results in rendering a different Custom Application.

Use the same entryPointUriPath value in the Custom Application config file and the Merchant Center configuration.

If there's a mismatch, the client-side routing will force a page reload to let the Merchant Center Proxy Router handle the route match, which renders the same application again, causing infinite reloads.

You can detect the reloading issue by inspecting the value of in the browser's developer tools and comparing it with the value in the URI path.

// custom-channels
// custom-channels-2

Security Headers

The Merchant Center Proxy Router enforces the following HTTP security headers when serving the response from the Custom Application location:

Referrer-Policy: 'same-origin'
Strict-Transport-Security: 'max-age=31536000'
X-Content-Type-Options: 'nosniff'
X-Frame-Options: 'DENY'
X-XSS-Protection: '1; mode=block'