~/tools / 04 / http-status-404-500
HTTP Status Code Simulator
Happy paths are easy; the 3 a.m. pager fires on the unhappy ones. Simulate the exact failure modes your retry logic, error boundaries, and alerting must survive: a clean 404 with a request ID for tracing, a 500 with an opaque incident reference, or a 429 that ships a Retry-After header your backoff code should respect.
compose payload
— validating —
exported mock url
simulated response headers
content-type: application/json
x-request-id: req_c81e728d9d4c2f63
$ man status-codes
Everything above is encoded into the #data= fragment of the exported URL — deflated and base64url-packed by your browser. Fragments are never sent to any server, so this mock is shareable and private. Paste the URL anywhere: a teammate's browser decodes it identically.