OpenWebLoad

Yes, it is an open-source performance testing platform, so there is no per-virtual-user licensing like commercial tools such as Micro Focus LoadRunner. You can use and modify it without license fees.

It supports HTTP/S as well as WebSocket, along with other protocols. That means it can stress not just websites and REST APIs but also real-time endpoints like chat or streaming services.

Yes — that is its core purpose: it simulates heavy user traffic and analyzes how your application behaves under stress. Teams use it to find bottlenecks and failure points before real users hit the system.

JMeter is a mature Java-based Apache project with a huge plugin ecosystem, while OpenWebLoad positions itself as a lighter open-source platform with protocol support like WebSocket built in. JMeter can handle WebSocket too, but typically via third-party plugins.