Lighthouse : Lighthouse is an open-source, automated tool for improving the quality of web pages. You can run it against any web page, public or requiring authenti...
tracing-framework : Rich tools for instrumenting, analyzing, and visualizing web apps.
mail-tester.com : Free online service that allows you to test your emails for Spam, Malformed Content and Mail Server Configuration problems
SPOFCheck : A CLI tool for detecting frontend SPOF, mainly blocking scripts and CSS
tota11y : an accessibility visualization toolkit that aims to reduce the friction of a11y testing
Test and track your emails. Email previews, analytics and spam filter testing.