# Router rate limiting

Router rate limiting is enforced at the gateway to avoid per-service throttling.
It supports instance-local and environment-wide limits.

Behavior
- Denied requests return 429 with Retry-After and rate limit headers.
- Response includes a JSON body with limit and window details.

Scopes
- Instance: in-memory sliding window per router instance.
- Environment: Valkey-backed fixed window across instances.

Configuration
- rate_limiting.process_back_pressure_when_more_than_per_5min gates Valkey use.
- rules support multiple windows with AND semantics.
- microservice overrides replace default rules.
- route overrides apply per service route name.

Failover
- Environment limiting is fail-open when Valkey is unavailable.
- Instance limits remain active for baseline protection.

Related references
- docs/router/rate-limiting.md
- docs/router/rate-limiting-routes.md