NixieFX is a free, open-source particle and VFX editor for HTML5 games. It runs entirely in the browser - nothing to install, no account needed - and ships runtimes for both PixiJS and Three.js.

You author an effect visually, export it as JSON plus textures, and load it at runtime in your game. Effects stay as plain files inside your own project folder rather than in someone else's cloud, so they version alongside the rest of your code.

What it includes:

A browser-based editor, with macOS and Windows desktop builds also available. Runtimes for PixiJS 8 and Three.js, published on npm as nixie-fx. Deterministic playback via seeds, which makes replays and screenshot tests reproducible instead of flaky. LLM skills so coding agents can author effects and wire them into a scene. MIT licensed, source at github.com/azakhary/nixie-fx.

Built at Rockbite Games. Disclosure: I work there.