OpenToon Studio

An open-source 2D animation studio for Windows, inspired by Toon Boom Harmony. Built as a zero-install desktop-style app — no build step, no server required.

Run it

Quick look: double-click index.html — opens in your browser, runs fully offline.

As a desktop app (with auto-updates): see BUILD.md. In short:

npm install
npm run dev      # run it (with live reload)
npm run dist     # build the Windows installer

The desktop build is a real Windows program that updates itself over-the-air — the right way to share OpenToon with someone else.

Features

Drawing & animation

• Paperless frame-by-frame animation
• Pressure-sensitive brush, pencil, eraser
• Shape tools (rectangle, ellipse, line) with fill
• Eyedropper
• Rectangular select with move / scale / rotate (free transform)
• Per-stroke opacity, smoothing
• Vector and bitmap layers (vector is the default)

Vector drawing (Harmony-style)

• Resolution-independent strokes, smoothed on release so lines are clean rather than rough (adjustable de-jitter)
• Auto-connect — stroke endpoints snap together so line art forms closed shapes
• Smart paint bucket — fills the region enclosed by your lines, with adjustable gap closing and a live hover highlight of the area
• Stroke-aware eraser (splits strokes) and stroke select / move / delete

Cut-out animation

• Per-layer transform keyframes (position / scale / rotation)
• Transform tool with on-canvas handles
• Smooth interpolation between keyframes — drawing, onion skin and export all stay transform-aware

Timeline / Xsheet

• Multi-layer timeline with exposure cells
• Create / duplicate / extend / clear exposures (held cels)
• Copy / cut / paste drawings between frames and layers
• Drag cels to move them, drag a cel's end to extend exposure
• Drawing thumbnails in the timeline
• Insert / remove frames

Playback & review

• Real-time playback, loop / ping-pong, in/out range to loop a section
• Flip canvas horizontally / vertically to check drawings
• Space or Enter to play/stop

Audio & video

• Import an audio soundtrack — waveform in the timeline, synced playback
• Import a video as reference frames on the timeline (pulls in its sound too)

Drawing aids

• Grid and rule-of-thirds guides
• Symmetry / mirror drawing

Layers

• Unlimited drawing layers, reorder, rename
• Per-layer visibility, lock, opacity
• Layer blend opacity in compositing

Onion skinning

• Configurable previous / next frame range
• Red / green tinting, opacity falloff

Color

• Named color palette with swatches
• HSV picker + hex input
• Add / remove / reorder swatches

Camera

• Camera framing guide
• Camera keyframes (pan / zoom / rotate) with interpolation

Playback

• Real-time playback at project FPS, loop, ping-pong
• Frame-step, go to start/end

Project I/O

• Save / load .otoon project files (JSON, self-contained)
• Autosave to browser storage
• Import reference images / image as layer

Export

• Animated GIF
• WebM video
• PNG image sequence (ZIP)
• Single-frame PNG

Keyboard shortcuts

Key	Action
V	Select pixels
A	Transform layer (cut-out animation)
B	Brush
N	Pencil
E	Eraser
G	Paint bucket
I	Eyedropper
R / O / L	Rectangle / Ellipse / Line
H / Space	Pan view
Z	Zoom tool
[ / ]	Brush size down / up
, / .	Previous / next frame
Enter	Play / stop
Ctrl+Z / Ctrl+Y	Undo / redo
Ctrl+S / Ctrl+O	Save / open project
Ctrl+N	New project
F	Fit view to camera
Del	Clear current drawing / delete selection

Status

This is an actively developed open-source clone. Core animation, timeline, painting, camera, and export pipelines are functional. See ROADMAP.md for what is planned next (vector deformers / bone rigging, node compositing, multiplane depth, particle effects, lip-sync).

License

MIT.