Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well.
Simulate any user scenario for webapps, websites, mobile apps or web services. 100% Apache JMeter compatible. Scalable from 1 to 1,000,000+ concurrent users.<br>
Loader.io is a free load testing service that allows you to stress test
your web-apps/apis with thousands of concurrent connections.
Run tests across a large selection of physical devices in parallel from various manufacturers with varying hardware, OS versions and form factors.
It 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.