Keyframe.itA free Spine alternative that runs in your browser
Keyframe.it is a free 2D skeletal animation editor for game sprites. If you want Spine-style bone rigging, weighted mesh deformation, and a keyframe timeline — but you don’t want to buy a desktop license — you can do the whole workflow in a browser tab and export Spine-compatible bundles that load in pixi-spine and other Spine runtimes. No install, no signup, and your work autosaves locally.
Try it now — open a full production rig
What Keyframe.it covers
- Bone rigging — FK hierarchies, bone splitting and reparenting, inverse kinematics with planted feet, transform and path constraints.
- Weighted meshes — auto-traced deform meshes with bone weighting for natural bending, squash & stretch, and deform keyframes.
- Animation — dope sheet, curve/graph editor with bezier easing, draw-order keys, image swaps with crossfades, animation events with payloads, skins.
- Spring physics — automatic secondary motion for hair, tails, cloth and smoke that bakes to keyframes on export.
- Export — Spine 3.8 and 4.2 bundles (.json or binary .skel + .atlas + packed .png), plus GIF, sprite sheet, and video. It imports existing Spine exports too.
- Extras Spine doesn’t have — a built-in image editor and sheet slicer, AI-assisted rigging and animation, and a scripting API any AI agent can drive.
Honest differences
| Keyframe.it | Spine (Esoteric Software) | |
|---|---|---|
| Price | Free | Paid desktop license (Essential/Professional) |
| Runs | In the browser, no install | Desktop app (Windows/Mac/Linux), works offline |
| Export | Spine-compatible 3.8 / 4.2 bundles | Native Spine format + official runtimes |
| Maturity | New and moving fast | 10+ years, deep ecosystem and docs |
| Runtime licensing | Exports load in community runtimes like pixi-spine; check your runtime’s license for commercial use | Official Spine Runtimes require a Spine editor license |
If you need offline desktop tooling or official runtime support contracts, buy Spine — it’s excellent software. If you want a fast, free, browser-based workflow that lands in pixi-spine — especially for slot and game symbols — that’s exactly what Keyframe.it is for.
Try it in 10 seconds
Live demos load instantly: noir character (meshes, springs, smoke) · monkey (breathing idle + blink) · slot symbol (idle/win/destroy pack)
Spine is a trademark of Esoteric Software LLC. Keyframe.it is an independent project and is not affiliated with or endorsed by Esoteric Software.
More: author animations for pixi-spine · slot symbol animation · API docs for AI agents