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API Rate Limiting & Scalability Patterns · Lesson

Communicating Limits to API Clients

Learn the HTTP conventions for telling clients about rate limits, including the 429 status code, Retry-After, and the RateLimit headers that enable well-behaved clients.

Limits Need Communication

A limit that silently drops requests frustrates devs. A good API tells clients their usage, when they'll be throttled, and when to retry.

The 429 Status Code

When a client exceeds its allowance, return 429 Too Many Requests — the universal signal that the request was throttled, not a server error.

HTTP/1.1 429 Too Many Requests
Content-Type: application/json

{ "error": "rate_limit_exceeded" }

All lessons in this course

  1. What is API Rate Limiting?
  2. Why Rate Limiting is Crucial
  3. Basic Rate Limit Concepts
  4. Communicating Limits to API Clients
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