Upgrade the web. Automatically.

What is Polyfill.io?

It's a service which accepts a request for a set of browser features and returns only the polyfills that are needed by the requesting browser.

Why do I need it?

There are lots of differing browsers and browser versions in use throughout the world, each one has a slighly different set of features to the rest. This can make developing for browsers a difficult task. The latest versions of the popular browsers can do lots of things which older browsers can not – but you may still have to support the older browsers. Polyfill.io makes it simpler to support differing browsers by attempting to recreate the missing features with polyfills: You can make use of the latest and greatest features in browsers which support them, and in those that do not.


From February 4th to February 10th, we have served 4,738,611,059 requests. 99.999318% of which were served from Fastly's global CDN cache.