itsual Rate Limiting and Throttling
Overview
Rate limiting protects system stability and enforces fair usage. Poorly designed limits frustrate users or fail to protect the system.
When to Use
- Public or multi-tenant APIs
- Expensive operations
- Protecting downstream dependencies
- Defending against abuse or accidental overload
Design Considerations
- What is being limited (IP, user, API key, tenant, endpoint)?
- Algorithm (token bucket, sliding window, fixed window, etc.)
- Response behavior (429 + Retry-After headers)
- Visibility and override mechanisms for legitimate high-volume consumers
- Distributed vs local limiting
Principles
- Fail closed under extreme load when necessary
- Provide clear feedback to clients
- Make limits configurable and observable
Verification
- Limits behave as documented
- Legitimate traffic is not unduly impacted
- System remains stable under bursty or abusive load