Prettier : Prettier is an opinionated code formatter. It enforces a consistent style by parsing your code and re-printing it with its own rules that take the max...
ack : ack is a tool like grep, optimized for programmers
Designed for programmers with large heterogeneous trees of source code, ack is written purely in po...
Flow : Adds static typing to JavaScript to improve developer productivity and code quality.
Prepack : Prepack is a tool that optimizes JavaScript source code: Computations that can be done at compile-time instead of run-time get eliminated. Prepack rep...
DOM Monster Bookmarklet : DOM Monster is a cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on, and give you its bill of ...
Beautify, unpack or deobfuscate JavaScript and HTML, make JSON/JSONP readable, etc.