What is a loadrunner?

LoadRunner is a software tool to test and measure system behavior, and performance under load. It can reproduce thousands of users concurrently utilizing application software, recording and then analyzing the performance of key components. Moreover, LoadRunner duplicates user actions by producing messages between application components with client interface like keypresses and thereby all messages and interactions to be generated are stored in scripts. And in addition to that, it can produce the scripts by recording them, such as logging HTTP queries within a client browser and an application's server.