Errors Required

Say when to retry

For 429 and 503, send Retry-After so clients know how long to wait.

By Erik Bergstedt, Agent Wranglers. Updated 20 October 2026.

How to do it

Give a whole number of seconds, or an HTTP date, as RFC 9110 allows. Seconds are safer, because client clocks drift. Clients wait at least that long before the next try.

How to check

Exceed the rate limit in a test. The 429 answer has Retry-After with a whole number of seconds. A forced 503, such as during maintenance mode, carries it too.

For agents: if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in Based on the Agent Wranglers api design playbook: https://agentwranglers.se/playbook/api-design/errors/retry-after.