ModelRefs / Rate Limit Error — AI Glossary
Rate Limit Error — AI Glossary
An HTTP 429 error returned by LLM APIs when a caller exceeds their token-per-minute or request-per-minute quota. Also called 429 error or throttling.
Overview
429 Too Many Requests signals rate limit exhaustion. The response headers (Retry-After, x-ratelimit-reset-requests, x-ratelimit-reset-tokens) indicate when the limit resets. Callers should implement exponential backoff with jitter, not naive sleep. Both TPM and RPM limits exist independently; hitting either triggers a 429.
Reference details
| Topic | ecosystem |
|---|---|
| Also known as | 429 error, throttling |
| Last reviewed | 2026-06-24 |
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Frequently asked questions
What is Rate Limit Error?
An HTTP 429 error returned by LLM APIs when a caller exceeds their token-per-minute or request-per-minute quota.
Is Rate Limit Error the same as 429 error?
Yes — 429 error, throttling are common aliases for Rate Limit Error.
What concepts are related to Rate Limit Error?
Closely related concepts include retry with backoff, tokens per minute, requests per minute.