Limits as a product feature
In a commercial API the rate limit is not only protection, it is part of the product. Different paying tiers get different budgets. A quota is usually a longer horizon cap, such as requests per month, while the rate limit is the short horizon cap, such as requests per second. A plan typically defines both.
How tiers are structured
- Free: low rate and a small monthly quota to let people try the product.
- Pro: higher rate and quota for serious individual use.
- Enterprise: large or custom limits, often negotiated and isolated.
The limiter looks up the caller account, finds its tier, and applies that tier configuration. The same machinery that protects the system also enforces the pricing model.
What to handle
- Overage policy: hard block at the quota, or allow overage and bill for it.
- Resetting the monthly quota cleanly at the billing boundary.
- Letting customers upgrade and have new limits apply immediately.
- Exposing usage so customers can track their consumption against the quota.
Key idea
Quotas and billing tiers turn rate limiting into a product feature where each plan maps to its own rate and longer horizon quota.