HTML_QuickForm2 : This PHP package provides methods to create, validate and render HTML forms.
Yellow Lab Tools : Online test to help speeding up heavy web pages
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
mail-tester.com : Free online service that allows you to test your emails for Spam, Malformed Content and Mail Server Configuration problems
WebPagetest : Run a free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds.
Increase your form conversions by fixing common usability issues
Enter a URL. FormLinter will find a form on the page and let you know if it can be improved.