Holder
Holder renders image placeholders entirely on the client side.
JSHint
JSHint is a community-driven tool to detect errors in JavaScript code and enforce your team's coding conventions.
Rulers Guides.js
Creates Photoshop-like guides and rulers interface on a web page
Nightwatch
UI automated testing framework based on node.js and selenium webdriver
Blaver
A JavaScript library built on top of the Faker.JS library. It generates massive amounts of fake data in the browser and node.js.
Js Cover
JSCover is a tool that measures code coverage for JavaScript programs.
Spa Eye
Backbone debugger for Firefox
Csscomb.js
CSS coding style formatter
Qunit
An easy-to-use JavaScript Unit Testing framework.
Pioneer
Integration Testing
Jasmine
DOM-less simple JavaScript testing framework
Csscritic
A lightweight framework for regression testing of Cascading Style Sheets
Angular Debaser
Just a better way to test AngularJS apps.
Bower
A package manager for the web, created at Twitter
Trace Kit
Attempts to create stack traces for unhandled JavaScript exceptions in all major browsers.
Gulp
The streaming build system
Fast Check
Property based testing framework for JavaScript (like QuickCheck) written in TypeScript