Rate Limiting

Rate limiting is a mechanism that limits the number of requests to an API or service within a set period. It is configured as, for example, "up to 100 requests per minute" or "up to 10,000 requests per day", and its purposes are preventing server overload, ensuring fair use, and deterring misuse.

When using a QR code generation API, rate limiting directly affects system design. If an e-commerce site generates a QR code for each order, you need to verify in advance that the number of requests at peak times will not exceed the rate limit. When the limit is exceeded, an HTTP 429 (Too Many Requests) error is returned and QR codes can no longer be generated.

Effective countermeasures are pre-generating QR codes (generating large numbers in advance with batch processing), caching (returning QR codes for the same data from a cache instead of regenerating them), and client-side generation (generating codes in the browser with a JavaScript library without calling the API).