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.
SPOF-O-Matic : Chrome extension for detecting and simulating frontend Single Points Of Failure. Detects likely third-party single points of failure as you browse and...
mail-tester.com : Free online service that allows you to test your emails for Spam, Malformed Content and Mail Server Configuration problems
webhint : webhint is a linting tool that will help you with your site's accessibility, speed, security and more, by checking your code for best practices and co...