# 429 Too Many Requests — Rate limit headers missing in response

- **ID:** `api/rest-api-rate-limit-header-missing`
- **Domain:** api
- **Category:** resource_error
- **Verification:** ai_generated
- **Fix Rate:** 75%

## Root Cause

API server enforces rate limiting but does not include standard headers like X-RateLimit-Remaining or Retry-After, making client backoff impossible.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| REST API v2.1 | active | — | — |
| nginx rate limiting module v1.24 | active | — | — |
| AWS API Gateway v2 | active | — | — |

## Workarounds

1. **Implement a fixed delay between requests (e.g., 1 second) to stay under the rate limit.** (80% success)
   ```
   Implement a fixed delay between requests (e.g., 1 second) to stay under the rate limit.
   ```
2. **Use a token bucket algorithm client-side to self-throttle.** (85% success)
   ```
   Use a token bucket algorithm client-side to self-throttle.
   ```

## Dead Ends

- **** — Without Retry-After, the client may back off too long or too short, leading to wasted time or continued throttling. (60% fail)
- **** — The issue is missing headers, not the limit value; increasing limit may not fix the client's inability to adapt. (70% fail)
- **** — Many APIs do not include retry info in the body; relying on it is fragile and non-standard. (80% fail)