Rate limiting is a network traffic management technique used to control the number of requests a user, IP address, or system can make to a server or API within a specific time frame. It helps prevent abuse, enhance security, and ensure fair resource allocation.
A rate limiter monitors incoming requests and enforces predefined thresholds based on parameters such as:
Requests per second (RPS): Limits how many requests a client can send per second.
Requests per minute/hour/day: Restricts access over longer periods.
IP-based limits: Applies restrictions based on a user’s IP address.
User/account-based limits: Enforces quotas at an account or API key level.
Token bucket or leaky bucket algorithms: Allows bursts of traffic while maintaining an average request rate.
When a user exceeds the limit, the system typically returns an HTTP 429 Too Many Requests response, signaling that further requests should be retried later.
API Protection: Prevents excessive API calls that could overwhelm backend servers.
DDoS Mitigation: Helps block malicious traffic floods, reducing the impact of volumetric attacks.
Brute Force Attack Prevention: Limits repeated login attempts to protect against credential stuffing.
Fair Resource Allocation: Ensures all users get a fair share of resources by preventing a single user from monopolizing a service.
Web Scraping Control: Restricts automated bots from aggressively crawling a website.
Fixed Window Counter: Counts requests in a fixed time window (e.g., 100 requests per minute).
Sliding Window Log: Keeps track of request timestamps and allows smoother enforcement.
Token Bucket: Assigns tokens per time unit, allowing controlled bursts of traffic.
Leaky Bucket: Processes requests at a steady rate, preventing large spikes.
User Experience Impact: Overly strict limits can frustrate legitimate users.
Bypassing Attempts: Attackers can distribute requests across multiple IPs to evade rate limits.
Scaling Issues: Dynamic rate limiting is needed for services with fluctuating demand.
Integration with Security Systems: Works best when combined with Web Application Firewalls (WAFs) and bot mitigation solutions.
Rate limiting is an essential tool for maintaining system stability, preventing abuse, and enhancing security. Implementing an effective rate-limiting strategy ensures fair usage while protecting services from threats like DDoS attacks, brute force attempts, and API abuse.