The HTTP 203 status code stands for "Non-Authoritative Information". It is a successful response, but the returned data may have been modified by an intermediary (such as a proxy) and is not the original version from the server.

When is HTTP 203 Used?

  • When a proxy or caching server modifies the response before delivering it to the client.
  • The response may be based on data from the original server but is not guaranteed to be identical to what the origin server would have provided.
  • It is similar to 200 OK, but indicates that the content might not be authoritative.

Example Scenarios

  • Content Filtering Proxy – A proxy modifies content (e.g., removing ads or changing text).
  • Language Translation Proxy – A response is translated before being delivered to the client.
  • Data Compression Proxy – A caching server compresses the content before serving it.

Example

Client Request:

  
    GET /news HTTP/1.1
    Host: example.com

Server Response (Modified by a Proxy)

  
    HTTP/1.1 203 Non-Authoritative Information
    Content-Type: text/html

    <html>
      <body><h1>Modified News Content</h1></body>
    </html>

Summary

HTTP 203 means the request was successful, but the response has been modified by an intermediary and is not necessarily the exact data from the original server.