API Latency Tester

Test API endpoint response times by running multiple requests and analyzing performance statistics including average, P95, and P99 latency.

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Test Your API Performance

Enter your API endpoint URL and run multiple requests to get detailed latency statistics. All requests run from your browser.

Quick test:
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Test API LatencyEnter an API endpoint URL and run multiple requests to measure response times and calculate statistics like average, P95, and P99 latency.

Understanding Latency Metrics

Key performance indicators for measuring API response times

Average Latency

The mean response time across all requests. Provides a general sense of API performance but can be skewed by outliers.Example: Average of 50ms means most requests complete around this time

P95 Percentile

95% of requests complete faster than this time. This metric helps identify worst-case scenarios while filtering extreme outliers.Example: P95 of 200ms means 95% of users see responses under 200ms

P99 Percentile

99% of requests are faster than this time. Critical for understanding tail-latency and ensuring consistent user experience.Example: P99 of 500ms means only 1% of requests exceed 500ms

Common Use Cases

Performance Benchmarking

Establish baseline performance metrics for your APIs and track improvements or regressions over time.

Third-Party API Testing

Test external APIs before integrating them into your application to ensure they meet your performance requirements.

Geographic Performance

Test API latency from different geographic locations to understand how distance affects response times.

Load Testing Preview

Get a quick preview of API performance under repeated requests before conducting comprehensive load tests.

Frequently Asked Questions

Common questions about API latency testing

What is API latency?

API latency is the time it takes for an API to respond to a request. It measures the delay between sending a request and receiving a response, typically measured in milliseconds.

What are P95 and P99 latency percentiles?

P95 (95th percentile) means 95% of requests complete faster than this time. P99 (99th percentile) means 99% of requests are faster. These metrics help identify worst-case performance and outliers.

How many requests should I run to test API latency?

For reliable statistics, run at least 20-50 requests. More requests (100+) provide more accurate percentile calculations and help identify performance patterns.

Why is my API latency high?

High latency can be caused by slow database queries, external API calls, inefficient code, network issues, or server overload. Use latency testing to establish baselines and identify performance degradation.