LoadRunner is a software testing tool from OpenText. It is used to test applications, measuring system behaviour and performance under load. LoadRunner can simulate millions of users concurrently using application software, recording and later analysing the performance of key components of the application whilst under load.LoadRunner is a software testing tool from OpenText. It is used to test applications, measuring system behaviour and performance under load. LoadRunner can simulate millions of users concurrently using application software, recording and later analysing the performance of key components of the application whilst under load.