203 Non-Authoritative Information
The request succeeded, but the returned headers were altered by a transforming proxy and may not match the origin server's original response.
What it means
203 is like 200, except a transforming proxy between the origin and client modified the payload or its metadata. It warns the client that the representation is not guaranteed to be the origin's authoritative version.
Why it matters
- It flags that an intermediary rewrote content — useful when debugging why a response differs from the origin.
Common mistakes
- Confusing it with 200; 203 specifically implies a proxy transformation.
How WebInspect checks this
- WebInspect reports intermediary and Via headers alongside the status so proxy transformations are visible.