HTTP 203 Non-Authoritative Information

What does HTTP 203 mean?

The request succeeded, but a proxy modified the response from the origin. A transforming proxy (for example one that compresses images or rewrites HTML) may answer 203 so clients know the content is not exactly what the origin sent. It is rare in practice.

2xx Success: The request was received, understood and accepted.

203 and SEO

Treated like 200 by search engines; avoid serving modified content to crawlers if it differs from what users see.

Example response

HTTP/1.1 203 Non-Authoritative Information

How to return a 203 response

Node.js (Express)

res.status(203).json({ error: 'Non-Authoritative Information' });

PHP

http_response_code(203);

Python (Flask)

return {'error': 'Non-Authoritative Information'}, 203

Go (net/http)

w.WriteHeader(203)

nginx

return 203;

Related status codes

• 200 OK — The request succeeded and the response body contains the requested resource.
• 204 No Content — The request succeeded and there is no response body.
• 206 Partial Content — The server is delivering only the byte range the client asked for with a Range header.

Check which status code a URL returns with the HTTP header checker.