API Rate Limiting Security: Preventing Abuse Without Blocking Legitimate Traffic

API rate limiting prevents abuse — brute-force attacks, data scraping, denial of service — by restricting the number of requests a client can make. Rate limiting testing evaluates: whether limits are enforced consistently across all endpoints, bypass techniques (distributing requests across IP addresses, manipulating client identifiers, using different authentication tokens), whether rate limits apply to authentication endpoints (preventing credential brute-force), and whether legitimate high-volume users are accommodated without creating abuse opportunities.