IsValid automates statistical tests for A/B experiments. It will calculate significance and confidence intervials.
In short, you can use it to figure out what, if anything, the result of an A/B test means.
I host this exact code at isvalid.org. If you want, you can host it yourself.
There is also an API (which you could host yourself!) that you can read about here.
IsValid uses Grunt to concatenate and minify JavaScript. It also uses grunt-coffee to compile CoffeeScript via Grunt. A simple npm install grunt-coffee will take care of both dependencies.
You can send data to IsValid with a handy browser bookmarklet using this as the URL:
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