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. You...
Wappalyzer : Wappalyzer is a cross-platform utility that uncovers the technologies used on websites. It detects content management systems, ecommerce platforms, we...
repl.it : Powerful and simple online compiler, IDE, interpreter, and REPL. Code, compile, and run code in 30+ programming languages. including JavaScript, Pytho...
REDbot : REDbot is lint for HTTP resources; it tests protocol correctness, cacheability, content negotiation and more. REDbot checks HTTP resources to see how ...
New Relic : New Relic’s SaaS-based Application Performance Monitoring helps you build, deploy, and maintain great web software.
Also, server monitoring, and more.
A free analysis tool to check if a website is disguising third-party trackers as first-party trackers.