Lottie

Designers export from After Effects, developers drop the JSON file into the app, and it just plays: vector-based, resolution-independent, tiny file sizes.

MIT, originally built by Airbnb. The workflow is: designer creates animation in After Effects, exports via the Bodymovin plugin as a JSON file, developer loads it with lottie-web. That JSON is typically 10-50KB where an equivalent GIF would be megabytes. Works on web, iOS, Android, and React Native.

Fully free and open source. No paid tier for the renderer. The After Effects plugin (Bodymovin) is also free. LottieFiles (a separate company) offers a paid platform for hosting, editing, and collaborating on animations, but you don't need it. Solo to large teams, the library costs nothing. LottieFiles' free tier gives you basic hosting and a library of pre-made animations. Their paid plans ($20-50/mo) add team collaboration, more storage, and advanced editing.

The catch: you need After Effects (or a compatible tool) to create animations. That's a $22.99/mo Adobe subscription. Not every After Effects feature is supported; 3D layers, expressions, and some effects won't export cleanly. And debugging a broken animation means digging through JSON by hand.