v0.3.0 is out · MIT licensed

Open-source 2D skeletal animation

Rig it like Spine, make it interactive like Rive, play it in every engine, and let an AI agent animate it for you.

Get started →Download the appLive examples

Editor for Windows, macOS, Linux and the web · runtimes for 19 engines · every edit is an MCP tool

WindsweptClick the buttons on the left of the artworklive

Play with sound

talkgullsgustmusicOfffxOff

This is not a video. It is Windswept, one .obone file, running in the real OpenBone web player. An AI agent built it with the MCP server.

🦴

Rig like Spine

Bones, weighted meshes with free-form deformation, IK, transform, path and physics constraints, skins, clipping, two-colour tint and texture atlases.

🕹️

Interactive like Rive

State machines with inputs, pointer listeners, live text, input bindings and sandboxed scripts.

🔊

Sound built in

Sounds on the timeline, events and states, a mixer with buses and mute buttons, lip sync from a voice recording, and video exports with the sound mixed in.

🌍

Play it anywhere

WebGL, Canvas, PixiJS, Phaser, Three.js and CanvasKit, plus native runtimes for C/C++, C#, Java, Swift, Flutter and Haxe, all held to one conformance suite.

🤖

Let an agent do it

Every edit is an MCP tool, and the editor shows an agent's work live as it happens.

📦

Export everything

JSON, binary, atlases, PNG and JPEG frames, GIF, APNG, PSD, sprite sheets, AVI, MOV, MP4 and WebM with sound, and a self-contained web page.

A real editor, not a toy

Setup and Animate modes, a dopesheet and graph view, weights, meshes, the Pen tool, a 3D depth view, state machines, a mixer and Play mode. Desktop app or in the browser.

Interactive by design

State machines, pointer listeners and live inputs run the same in the editor, the web player and every native runtime. Click them.

KnightClick the road to walk, him to attack, the helmet to salutelive

Play with sound

walkattacksalute

Crash gamePress START, then drag the multiplierlive

Play with sound

startcrashcashoutmultiplier

1.00

RocketClick the rocket to launchlive

Play with sound

launch

See all ten live examples →

Let an agent animate

The MCP server exposes every editing operation as a tool, plus rendered frames and state-machine runs so the agent can check its own work. Click ⚡ Connect MCP in the editor and watch the edits arrive live.

MCP client config

{ "mcpServers": { "openbone": { "command": "npx", "args": ["-y", "@openbone/mcp"] } } }

“Create a project at ~/anim/robot.obone: a robot with IK arms, an idle and a wave animation, and a state machine that waves when clicked.”

MCP guide →

A wave animation, made by MCP tool calls, arriving live in the editor.

Install

Packages are published from every release. Pick your platform.

Web

npm install @openbone/player

<script type="module">
  import { definePlayerElement } from "@openbone/player";
  definePlayerElement();
</script>
<openbone-player src="walker.obone" state-machine="character"></openbone-player>

Unity

Package Manager → Add package from git URL:

https://github.com/UXCentury/open-bone.git#upm

or with OpenUPM

openupm add com.openbone.runtime

Godot

AssetLib tab → search OpenBone, or unzip openbone-godot-0.3.0.zip from the releases into your project.

Flutter

flutter pub add openbone

Swift

Xcode → Add Package Dependencies → https://github.com/UXCentury/open-bone, product OpenBone.

Android / JVM

implementation("io.openbone:openbone-runtime:0.3.0")
// + openbone-scripting, openbone-gdx, openbone-android

.NET

dotnet add package OpenBone.Runtime
dotnet add package OpenBone.MonoGame

C / C++

add_subdirectory(runtimes/cpp)  # QuickJS and nlohmann/json are vendored

CLI & MCP

npx openbone --help
npx -y @openbone/mcp

GitHub ReleasesDesktop app · Windows, macOS, Linuxnpm@openbone/* · openbonepub.devopenboneNuGetOpenBone.RuntimeMaven Centralio.openbone:*Unityupm branch · OpenUPMGodotgodot-addon branch · AssetLibSwift Packagegithub.com/UXCentury/open-bone

One file, every engine

WebGLCanvas 2DPixiJSPhaserThree.jsCanvasKitUnityGodotUnrealMonoGamelibGDXAndroidSwiftUIFlutterCocos2d-xSDL2SFMLOpenGLHaxe

Every runtime implements the runtime specification and passes the conformance suite: the same poses, draw lists, events, audio commands and state-machine steps, for every example.

Animate in the open.

Everything is MIT, from the editor to the last runtime, built only on permissively licensed open source.

Quick startStar on GitHub