429 Too Many Requests

The client sent too many requests in a given time and is being rate limited. May carry a Retry-After header.

What to do

Slow down. Wait as long as Retry-After says, or, without it, wait longer after each attempt. Spreading requests out or batching them keeps it from coming back.

Class
4xx Client Error. The request has a fault, or cannot be met as sent.
Registered
Yes, in the IANA HTTP status code registry.
Cacheable by default
No. A cache stores it only when Cache-Control or Expires says to.
References
RFC 6585 ยง4 · MDN

Example response

HTTP/1.1 429 Too Many Requests
Retry-After: 120

Every 4xx code

All HTTP status codes, in one table