What is 429 Too Many Requests? Meaning and example

What is 429 Too Many Requests?

429 Too Many Requests: The status code meaning the client has sent more requests than the rate limit allows in a time window. The response often includes a Retry-After header. Clients should slow down and retry using backoff.

Level: intermediateTopic: Web APIs HTTP

429 Too Many Requests: an example

A script hammering an LLM API at 100 requests per second receives 429 and Retry-After: 20.

Related terms

Rate limiting
Retry-After
Exponential backoff
Status code

More Web APIs HTTP terms

500 Internal Server Error
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout
Accept header
Access token
API
API gateway

Where you learn it

429 Too Many Requests is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.