Mock JSON endpoint returning HTTP 400

Live demo endpoint

Any method, any path. Returns 400 Bad Request with Content-Type: application/json. OPTIONS returns 204 with CORS headers.

Call it with curl

curl -i https://demo-json-400.supercrontab.com/

Call it with fetch

const res = await fetch("https://demo-json-400.supercrontab.com/");
console.log(res.status); // 400
const body = await res.json();

What HTTP 400 Bad Request means

When you see it

The server could not understand the request: malformed JSON, a missing field or a wrong parameter type.

What a client should do

Fix the request before sending it again. Log the response body, it usually names the bad field.

Retry?

No

Sample response body

{"ok":true,"id":42,"items":["alpha","beta","gamma"]}

The default for REST APIs. Parse it with response.json() and check the ok field.

Questions