Loader.io is a free load testing service that allows you to stress test your web-apps & apis with thousands of concurrent connections.

Comprehensive and user-friendly cloud platform for Load Testing, Speed Testing and Website & API Optimization and Monitoring

The Apache JMeter™ application is open source software, a 100% pure Java application designed to load test functional behavior and measure performance. It was originally designed for testing Web Applications but has since expanded to other test functions.

Don’t just observe. Take action. The only app monitoring platform built for developers that gets to the root cause for every issue.

WebLOAD – Performance and Load Testing for the Most Challenging Web Applications

Unifying API testing, API Performance testing, API Mocks and UI testing.