Selenium has been a method to test web applications for over a decade, it is interacting directly with the browser and has gained support from both browsers and the community. With the growing amount of browsers, mobile devices and operating systems which a web application is expected to work with, services providing these systems for testing web applications against has gained interest. These services provide testing as a service (TaaS), and runs Selenium-tests in the cloud. This research tried to compare the different services with each other in regard to flexibility, cost, simplicity and reliability. I have also tried to see differences between running the tests locally and using these services. The results showed that there are some differences between the services, and the one best suited might depend on the web application.