Dynatrace Load - Dynatrace Load lets you test the performance of web and mobile applications with the realism of load generation from the cloud.
Real Load - Real Load - A REST, SOAP, HTML, HTTP, Powershell, SQL performance test tool
Loader - Load testing and tracking application
LoadStorm - Load test websites, web apps, APIs, and mobile apps via the cloud. Use scripts to simulate user behavior for up to a million virtual users. Try it for free!
Sitespeed - Sitespeed.io is an open source tool that helps to analyze and optimize website speed and performance.
Apache JMeter - Apache JMeter™.