HTTP 429 Too Many Requests
Rate-limited. The client is sending too many requests too fast.
What it means
429 means "slow down" — the client has exceeded a rate limit. A well-behaved API includes a Retry-After header telling the client how many seconds to wait. Some APIs also return X-RateLimit-Remaining and X-RateLimit-Reset headers so clients can self-throttle.
From a monitoring perspective, 429s during a check are almost always self-inflicted — your monitor is sharing an IP with other heavy clients of the same API. Talk to the upstream and either get on a higher tier or allowlist the monitoring source.
Common causes
- Burst of requests exceeding the rate-limit window
- Multiple clients sharing an IP and hitting a per-IP limit
- WAF rate-limiting suspected abusive patterns
- API quota exhausted for the day / hour
How to fix it
- 1Honor the Retry-After header and back off
- 2Implement exponential backoff in the client
- 3Upgrade the API plan or request a higher rate limit
- 4Allowlist monitor source IPs upstream if the API supports it
How Uptimera reports 429
Uptimera flags 429 as down. For external APIs that aggressively rate-limit, switch the monitor to a longer interval and confirm Uptimera's source IPs are allowlisted.
Related codes
Forbidden
The server understood the request and the client is authenticated, but they don't have permission.
Service Unavailable
The server is temporarily unavailable — overloaded, in maintenance, or intentionally not accepting traffic.
Request Timeout
The server didn't get a complete request in time. The client should retry.
Catch 429s before your customers do
Uptimera monitors your URLs from multiple regions and alerts the moment a 429 starts firing. Free plan included.