JavaScript & TypeScript Performance Testing Tool
Analyze Execution Time, Memory Usage & Bundle Size
Perf Lens is a free online tool for JavaScript performance testing and TypeScript benchmarking. Analyze your code's execution time, memory usage, and bundle size with detailed visualizations. Perfect for developers who want to optimize JavaScript performance and identify bottlenecks in their applications.
Whether you're comparing array methods, optimizing algorithms, or analyzing memory leaks, Perf Lens provides the insights you need to write faster, more efficient code. Start testing your code snippets instantly—no installation required.
Key Features
✨Real-time Performance Testing
Run benchmarks with customizable iterations (10-1000 runs). Get instant feedback on execution time and statistical analysis.
Memory Profiling & Analysis
Detect memory leaks and analyze heap usage with detailed metrics. Includes outlier detection and stability scoring.
Bundle Size Comparison
Compare source code vs compiled output size. Optimize your JavaScript bundles for faster load times.
Statistical Analysis
Advanced metrics including mean, median, standard deviation, CV coefficient, and IQR-based outlier detection.
Export Detailed Reports
Generate comprehensive Markdown or JSON reports. Perfect for documentation and team collaboration.
Side-by-Side Comparison
Upload and compare multiple test reports. Analyze performance differences with percentage change calculations.
Perfect for Developers Who Want to...
- ✓Compare array methods performance (map vs forEach vs for loop)
- ✓Optimize algorithms and identify the fastest implementation
- ✓Detect memory leaks in JavaScript and TypeScript code
- ✓Analyze bundle size impact of different coding approaches
- ✓Benchmark async operations (Promises vs async/await)
Start Testing Your Code Now
No signup required. Free forever. Open source.
Simply paste your JavaScript or TypeScript code in the editor above and click "Run Test" to get started.
Compare Performance Reports
Already have test results? Compare them side-by-side.
Upload two JSON reports to analyze performance differences with detailed metrics and percentage changes.
Go to Compare Page→Learn Performance Optimization
Read our blog for best practices and tutorials.
Explore in-depth articles on JavaScript performance testing, memory profiling, and code optimization.
Read Blog Articles→Code Editor
Write or paste your code snippet to test its performance
⚙️Test Configuration
Configure your performance test parameters