# AI API error 429: rate limits, credits and spend caps

A 429 is a request limit response, not proof of a provider outage. Read the provider error code, message and retry headers before retrying.

By IsAnythingDown. Reviewed 2026-10-06.

Canonical page: https://isanythingdown.com/guides/ai-api-error-429

## Quick answer

A 429 is a request limit response, not proof of a provider outage. Read the provider error code, message and retry headers before retrying.

## What each provider documents

OpenAI distinguishes request rate limits, exhausted credits and organization or project limits. Inspect error.code; retrying a billing or usage limit does not restore access.

Claude uses rate_limit_error for rate limits and some spend caps. A usage-tier spend-cap response has no retry-after header. Fast traffic growth can also trigger rate limits.

Gemini describes 429 RESOURCE_EXHAUSTED among errors that can justify exponential backoff. Inspect the error details before treating a limit as transient.

- [OpenAI API error codes](https://developers.openai.com/api/docs/guides/error-codes)
- [Claude API errors](https://platform.claude.com/docs/en/api/errors)
- [Gemini API troubleshooting](https://ai.google.dev/gemini-api/docs/troubleshooting)

## Recommended application response

Reduce request concurrency for a transient rate limit, honor a supplied retry delay, and set a maximum attempt count and total deadline. Account for retries already performed by your SDK. A missing retry header does not identify the cause on its own.

Preserve a sanitized error body and request ID. Check your account configuration privately when the error reports a credit or spend limit; do not publish credentials. Compare the relevant API status scope with your request evidence.

- [How to interpret AI API errors](https://isanythingdown.com/guides/ai-api-error-codes)

## Related service pages

- [OpenAI API](https://isanythingdown.com/services/openai)
- [Claude](https://isanythingdown.com/services/claude)
- [Gemini API / AI Studio](https://isanythingdown.com/services/gemini-api)
- [OpenRouter](https://isanythingdown.com/services/openrouter)

Each entry shows its own collection coverage. A linked service is not necessarily automatically collected.

Editorial review date applies to this guide. Live report collection times appear on the service pages.