Open Source Windows Performance Testing Software

SeaToad is a library to aid in concurrency and load testing of .NET code. Intended for use by developers or automation testers. For example, it makes a good second hand if you're trying to reproduce a concurrency issue. You can very quickly generate load representing one or more portions of the suspect code, while manually performing other tasks. Or perhaps you're worried about the performance of a particular stored procedure with load from an external source. SeaToad can run the stored procedure and the external load for you to locate performance and concurrency bottlenecks.

JMeter is a load testing framework developed in Java. This plugin adds functionality to JMeter that logs results to a database, allowing for more effective reporting.

jLlama is a desktop application to monitor servers over SSH. Any figure retrieved from the command line can be polled and graphed in real time. Out of the box, jLlama can graph CPU and Memory usage for Linux and Solaris servers.