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

Simplifies performance and load testing so that application delivery teams can take a standardized approach to ensure continuous performance, reliability, and scalability from development to production.

Built for developers and testers alike, SoapUI is the only open source tool that covers the entire testing spectrum (functional, security, load, mocking).

k6 Open Source is designed for load testing. Extensible to support other types of testing.

Performance testing with Flood increases customer satisfaction and confidence in your production apps and reduces business risk.

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