What is API rate limiting?

Rate limiting restricts how many API requests a client can make within a time window. It protects servers from overload, prevents abuse, and ensures fair usage. Common implementations include token bucket and sliding window algorithms.

What does a 429 status code mean?

HTTP 429 Too Many Requests means you have exceeded the rate limit. Check the Retry-After header to know when you can send requests again. Implement exponential backoff in your code to handle this gracefully.

⚖️ API

API Rate Limit Calculator

Input your rate limit policy and expected traffic pattern to calculate burst headroom, requests-per-second capacity, safe concurrency and retry-after timing. Great for API design and client implementation planning.

⚙️ Rate Limit Configuration

Request Limit

Time Window

Your Expected Requests per Minute

📊 Analysis

Usage (your traffic vs limit)

🕐 Traffic vs Limit (per-minute view, 10 windows)

Now+10 min

📋 Standard Rate Limit Response Headers

💡 Client-Side Strategies

Sliding vs Fixed Window: Most APIs use fixed windows (counter resets at exact intervals). Some use sliding windows (rolling average). With fixed windows, a burst at the end of one window + start of next can effectively double your rate — always implement backoff even when under the limit.

📖 How to Use This Tool

▼

Enter limit and time window

Enter your expected request rate

View burst headroom and safe RPS

Try presets for GitHub, Stripe, OpenAI

📝 Examples

GitHub

Input: 5000/hr, 40/min

Output: Safe RPS:1.11, 83% used