HTTP 226 IM Used
Updated Free mock REST & WebSocket APIs
HTTP 226 IM Used — The server applied an instance manipulation (such as a delta encoding) to the response.
- Class
- 2xx Success
- Defined in
- RFC 3229
- Official
- Yes (IANA registry)
- Cacheable by default
- No (unless Cache-Control/Expires say so)
Try it: get a real 226 response
Our test endpoint answers every request with 226 IM Used.
curl -i https://mockfox.dev/api/status/226Use it in tests, health-check monitors or to see how your client handles a 226. Add ?delay=2000 to slow it down.
What does HTTP 226 mean?
Part of the little-used Delta encoding in HTTP extension: a client sends A-IM: vcdiff and the server returns 226 with only the differences from a version the client already has. Virtually no mainstream servers or browsers implement it.
Handling 226
- Visitors: Nothing to fix — this is a success status.
- Developers: Make sure clients handle this status as success (
response.okis true for 200–299) and know whether to expect a body.
Example 226 response
HTTP/1.1 226 IM Used
Content-Type: application/json
{"status":226,"error":"IM Used"}2xx Success: The request was received, understood and accepted. See the full list of HTTP status codes.
Related status codes
- 200 OKThe request succeeded and the response contains the result.
- 304 Not ModifiedThe cached copy the client already has is still valid, so no body is sent.
Related tools
Frequently asked questions
What does HTTP 226 IM Used mean?
The server applied an instance manipulation (such as a delta encoding) to the response.
Is 226 an error?
No. 226 is a success status.
Where is 226 defined?
In RFC 3229. It's listed in the IANA HTTP Status Code Registry.
How can I test how my app handles a 226?
Call https://mockfox.dev/api/status/226 — it responds with 226 to any method, with CORS enabled. Add ?delay=2000 to simulate a slow response.