Validating laboratory tests
Locust - Scalable user load testing tool written in Python.
Locust is completely event-based, and therefore it's possible to support thousands of concurrent users on a single machine.
in the LFAQ section; there are also articles about web site testing and management in the 'Resources' section. Free open source version supports the HTTP protocol, the $pro version supports binary protocols.
Go Replay - Performance testing tool that listens for traffic on production servers and feeds it to test and dev environments. Pro version supports replaying and keep-alive sessions to ensure that you get the exact same number of connections every time.
Focus on support of the HTTP protocol that makes it a tool of choice for load testing any HTTP server.
This allows you to write very expressive scenarios in Python without complicating your code with callbacks.
Agileload - Load test tool from Agile Load SA for testing all types of web and mobile applications.
Features include automatic recording of test scenarios, distributed load injectors, topological and threshold analysis of anomalies, infrastructure monitoring, creation of custom test reports for each user profile.
Based on an expressive DSL, the scenarios are self explanatory.
They are easy to maintain and can be kept in a version control system.