Rational Robot, produced and maintained by IBM, is a very comprehensive solution for load testing on web services and software. When every aspect of a sophisticated web application must be thoroughly tested, Rational Robot is an excellent choice. In addition to load testing, Rational Robot performs functional verification and error detection. Extensive scripting functionality allows the tester to thoroughly test an application. This testing can be done in a direct fashion, without having to operate through the UI of the application.

Rational Robot has an extensive battery of testing abilities that can quickly track down the source of a problem. During a software test, Rational Robot employs several methods of comparison to detect any errors that occurred. The program analyzes text, images, object properties, and grid points to detect any abnormal behavior. Verification points analyze the web application at several stages, making it easier to trace an error as soon as it occurs. Knowing when and where an error occurred is priceless information for a tester attempting to track down a difficult error.

Rational Robot also includes highly useful utilities, such as a recorder that produces easily automated tests. In addition to tests that are easy to automate, Rational Robot also emphasizes the realistic nature of the tests that it performs. Testers can supply Rational Robot with a "datapool" that allows the program to simulate the randomness of user input. This is very important for web applications that must be thoroughly tested for input processing.

In addition to the powerful Basic-like language for script processing, Rational Robot also has a useful feature known as Web Site Scan. With Web Site Scan, obvious errors can be quickly identified without the need to spend time programming. Obvious errors include broken links and slow loading pages. Web Site Scan can also compare a page to a baseline version of the page. This can be useful to automatically detect errors that might be otherwise difficult to find in a purely programmatic fashion.

The SQABasic language used in Rational Robot can accomplish a wide variety of tasks, especially with the inclusion of support libraries. The libraries include easy to use components such as timers and log manipulators that are simple to insert into a script. The SQABasic IDE includes useful debugging features such as breakpoints and variable watchers, making script programming as intuitive as possible. When the most extensive testing capabilities possible are needed, Rational Robot is a comprehensive if expensive option.