The HTML5 Shiv : The HTML5 Shiv enables use of HTML5 sectioning elements in legacy Internet Explorer and provides basic HTML5 styling for Internet Explorer 6-9, Safari...
polyfill : polyfill makes web development less frustrating by selectively polyfilling just what the browser needs. Use it on your own site, or as a service.
Babel : Babel will turn your ES6+ code into ES5 friendly code, so you can start using it right now without waiting for browser support.
Firebug Lite : A JavaScript file you can insert into your pages to simulate the Firebug console in browsers that are not named Firefox.
SlimerJS : A scriptable browser for Web developers
IE7.js is a JavaScript library to make Microsoft Internet Explorer behave like a standards-compliant browser. It fixes many HTML and CSS issues and makes transparent PNG work correctly under IE5 and IE6.