Apache JMeter is an open source tool created by Apache Software Foundation for software load testing.
It is the most suitable for verifying performance of a web application under different loads.
The tool can generate load on a server, group of servers, network and create various user sessions.
The test reports include diagrams and tables.
Apache JMeter supports a number of popular languages such as Java, ASP.NET, Files, PHP.
It is applicable for various types of servers and protocols including HTTP, HTTPS, SOAP/REST, FTP.