WatiN or Selenium?

If you're looking to make a serious long-term investment in a framework that will continue to be improved and supported by the community, Selenium is probably your best bet. For example, I just came across this info on Matt Raible's blog:

As of Friday, Google has over 50 teams running over 51K tests per day on internal Selenium Farm. 96% of these tests are handled by Selenium RC and the Farm machines correctly. The other 4% are partly due to RC bugs, partly to test errors, but isolating the cause can be difficult. Selenium has been adopted as the primary technology for functional testing of web applications within Google. That's the good news.

I also went to one of the Selenium meetups recently and learned that Google is putting serious resources into improving Selenium and integrating it with WebDriver, which is an automated testing tool developed by Simon Stewart. One of the major advantages of WebDriver is that it controls the browser itself rather than running inside the browser as a Javascript application, which means that major stumbling blocks like the "same origin" problem will no longer be an issue.

Just want to say that I'm currently working hard on a beta release of WatiN 2.0 somewhere in Q1 of 2009. It will be a major upgrade to the current CTP 2.0 versions and will basically give you the same functionality to automate FireFox and IE as version 1.3.0 offers for automating IE.

So no concerns there.

Hope this helps in making your choice Jeroen van Menen Lead dev WatiN

We've tested both and decided to go with WaTiN. As others have pointed out, Selenium does have some nice features not found in WaTiN, but we ran into issues getting Selenium working and once we did it was definitely slower when running tests than WaTiN. If I remember correctly, the setup issues we ran into stemmed from the fact that Selenium had a separate app to control the actual browser where WaTiN did everything in process.