Mock YAML endpoint returning HTTP 503

https://demo-yaml-503.supercrontab.com/ answers every request with HTTP 503 Service Unavailable and a small YAML body. No signup, CORS enabled, nothing logged. Use it to see how your client, retry logic or cron job behaves on a 503 before it happens in production.

Live demo endpoint

https://demo-yaml-503.supercrontab.com/

Any method, any path. Returns 503 Service Unavailable with Content-Type: application/yaml. OPTIONS returns 204 with CORS headers.

Call it with curl

curl -i https://demo-yaml-503.supercrontab.com/

Call it with fetch

const res = await fetch("https://demo-yaml-503.supercrontab.com/");
console.log(res.status); // 503
const body = await res.text();

What HTTP 503 Service Unavailable means

When you see it: The service is overloaded or down for maintenance. Servers may include Retry-After to say how long.
What a client should do: Retry with exponential backoff and honour Retry-After. Circuit breakers should open after repeated 503s.
Retry?: Yes, with backoff

Sample response body

ok: true
id: 42
items:
  - alpha
  - beta
  - gamma

Used by config loaders and some infrastructure APIs. Test indentation handling and list parsing.

Questions

Does this endpoint really return HTTP 503 every time?

Yes. Every GET, POST, PUT, PATCH or DELETE to https://demo-yaml-503.supercrontab.com/ gets status 503 Service Unavailable with a small YAML body, whatever the path, query or headers. OPTIONS gets 204 with CORS headers so browsers can preflight.

Should my client retry a 503?

Yes, with exponential backoff and a cap on attempts. Retry with exponential backoff and honour Retry-After. Circuit breakers should open after repeated 503s.

Can I get a different format, a delay or a custom body?

The same status is available in JSON, XML, Text, CSV, HTML, RSS, JavaScript. Delays, custom headers, error rates, request logging and your own body need a personal endpoint: sign up and create one at /endpoints in a minute, free.