Google Website Optimizer is the most popular split testing platform online and it’s also 100% free.
To get started, go to Google Website Optimizer and start by clicking on “Create an Experiment.” You’ll be guided through the step by step process of setting up a split test.
If you choose to do an A/B split test, you’ll basically set up two different pages and Google will automatically split the traffic for you and report the results.
If you choose to do a multi-variable split test, you’ll have a single page with different PHP codes on the page that publishes different versions of each variable every time the page loads.
Once you have a split test setup, Google will show you data on your visitors, conversion and conversion rate on your front page. It’ll also tell you how far you are from having statistically significant data.
For example, if you have enough results that Google is 75% sure you have a winner, it will tell you that. You can then decide if that’s good enough for you and call the test complete, or you can wait for more data to be closer to 100% certain.