Firebolt is a lightweight and high performance JavaScript library written for modern browsers.

View the Firebolt API  

or try out Firebolt in the

Firebolt Test Chamber  


Firebolt is a high performance JavaScript library packed into a very small file size. Firebolt's functionality is based off of jQuery (a lot of the API is identical to jQuery's), but is built by extending the prototype of native objects, similar to the Prototype framework. This opens up a whole new world of coding possibilities, allowing users of the library to write extremely efficient code, but with the simplicity of a jQuery-like API.

But isn't extending prototypes in JavaScript a bad thing? Usually the answer is "yes", but that is not the case for Firebolt. Read this to find out why Firebolt's prototype-extending design is not "evil".


Similar to Zepto, Firebolt keeps its file size small by targeting only modern browsers. Firebolt's size is comparable to Zepto's, which is about 1/3 the size of jQuery after being minified and gzipped. This means that Firebolt loads very quickly and keeps bandwidth usage low for both clients and servers.


In addition to being very small, Firebolt also aims to be blazing fast. Many functions are heavily performance tested using jsPerf to obtain the highest possible performance average across today's most commonly used browsers. Here are some jsPerf tests that demonstrate the power of Firebolt:


Firebolt animates elements purely with CSS using CSS3 transitions. This means that the browser takes care of a majority of the work involved in the animation, so you can always count on animations to be smooth and look consistent on all platforms. Furthermore, animating using CSS transitions allows Firebolt to natively support animating special properties such colors and transforms. Check out the demos to see these animations in action!
Note: Since Internet Explorer 9 does not support CSS transitions, Firebolt gracefully degrades animations in IE9 to use a very simple JavaScript animation algorithm. This also means that special CSS properties (i.e. colors) are not animated in IE9, but are instead set to the target value after the specified animation time has passed.

Download Firebolt

firebolt.js - development version fully documented with comments

firebolt.min.js - minified version ~9.7 kB when gzipped

Note: The library is currently in alpha, so it may have some bugs. Please report any bugs that you find.

Firebolt CDN

Just use the code below to include Firebolt directly in your web page (thanks to Firebolt's CDN provider, CloudFlare).

<script src="//"></script>

Browser Support


For general inquiries or if you'd like to help in developing this project, please send an email to [email protected].
To suggest features, report bugs, or ask code-related questions, create an issue in Firebolt's GitHub repo.