203 Non-authoritative Information

Takeaways

1. The request was successful but the enclosed payload has been modified from that of the origin server's 200 OK response by a transforming proxy.
2. This status code allows the proxy to notify recipients when a transformation has been applied, since that knowledge might impact later decisions regarding the content. For example, future cache validation requests for the content might only be applicable along the same request path (through the same proxies).
3. The 203 response is similar to the Warning code of 214 Transformation Applied, which has the advantage of being applicable to responses with any status code.
4. A 203 response is cacheable by default; i.e., unless otherwise indicated by the method definition or explicit cache controls.

Information

The 203 Non-Authoritative Information response status indicates that the request was successful but the enclosed payload has been modified by a transforming proxy from that of the origin server's 200 OK response.

The 203 response is similar to the value 214, meaning Transformation Applied, of the Warning header code, which has the additional advantage of being applicable to responses with any status code.