Sitespect is non-intrusive tool that provides great flexibility in all types of testing- including complex multivariate tests. It's a very flexible tool that allows you to manipulate your code in the most optimal ways. In addition, they're customer service is excellent and they will work hard with you to find solutions.

Ok, so it's been a few years since I've used SiteSpect, but when I did, the team was awesome! Everyone I worked with there was diligent, smart and personable. The tool itself was extremely powerful.

Ease of use, scalability, feature rich A/B testing software for medium and large enterprises. The support team is great as well - very knowledgeable about the product with great customer service.