Hi HN! I have been building WebMotion, a small library for making videos in the browser.

The basic idea is that everything on screen is a pure function of the current frame, so rendering frame N always produces the same result. That means you can seek anywhere in the timeline, and exports are frame accurate without needing a server.

Demos (each includes its own source): https://superhq-ai.github.io/webmotion/

The repo also includes an agent skill that lets coding agents create launch videos from a prompt. Quite a few of the demos were made that way.

Feedback is very welcome :)

This is so cool, I've always wanted something like this.