JavaScript at the Edge
Open source

Fly is a global JavaScript runtime that makes apps faster. You can optimize images, pre-render, cache partials, and more.

How does it work?

We run datacenters all over the world. When you deploy a Fly Edge Application, your visitors are routed to the nearest datacenter. Our application servers connect them to your JavaScript environment (built on v8) in under 1ms. Your app does the rest.

Illustrated balloon mascot scrapbooking

Optimize images

Deliver the exact images you need for each person. Use our Image and HTML APIs to enable responsive images without touching crufty old code no one remembers how to deploy.

image.resize(800).webp()
Two illustrated balloon mascots playing Madlibs

Remix everything

Pull your content from anywhere, present it how you want and skip the copy pasta. We use this to inject our README.md into our documentation.

html = markdown(await readme.text())
Illustrated balloon mascot taking a selfie while it blows glass

Prerender for speed

The fastest way to serve a React app to a new visitor is to pre-render to HTML, then deliver the JavaScript later. Just write a few lines of edge JavaScript to load your existing React app and send it to your users.

ReactDOMServer.renderToString(<MyApp />)

Features

Our open source Edge Application runtime works like most modern application frameworks. We have tools for development + test, and powerful APIs for building CDN like applications.