Errors and the response diagnostician

Diagnose a response

Everything happens inside your tab: the body is never sent anywhere and never reaches the address bar. A truncated paste works too — both JSON and a chunk of an HTTP dump are recognised.

Five sources of 429

Five independent mechanisms answer with 429, and each one is cured differently. They can be told apart from the response alone: is there a reason in the body and did a Retry-After header arrive. Three of the five bodies are byte-for-byte identical.

Guide: limits and the 429 code

HTTP codes

Seven codes the public surface answers with. There are no 5xx pages here on purpose: 500 and 503 are not about the client — they are cured by a retry, not by reading documentation.

• 401401 — key rejected
• 402402 — payment required
• 403403 — insufficient permissions
• 404404 — resource not found
• 409409 — state conflict
• 422422 — request not accepted
• 429429 — one of five limits was hit

Machine reason codes

Branch on reason, never on message: wordings change without notice and are not an error code. The codes are grouped by the HTTP code they arrive with.