Websam
WebSAM
Segment Anything (SAM / SAM 2 / SAM 2.1) running entirely in your browser. No server, no uploads, no API keys. Pick a model, load an image, click to segment.
How it works
Model weights are downloaded once and cached locally via the Origin Private File System. Inference runs through ONNX Runtime Web -- WebGPU when available, WASM as fallback. Everything happens in a Web Worker so the UI stays responsive.
Point at something and click. Left-click marks foreground, right-click marks background. You can also draw bounding boxes or let it segment the whole image at once.
Models
| Family | Variants | Size range | Backend |
|---|---|---|---|
| SAM 2.1 | Tiny, Small, Base+, Large | 145 MB - 878 MB | WebGPU |
| SAM 2 | Tiny, Small, Base+, Large | 148 MB - 869 MB | WebGPU |
| SAM 1 | SlimSAM-77 (INT8) | ~14 MB | WASM (CPU) |
SlimSAM-77 works on any browser. The SAM 2.x models need WebGPU support (Chrome 121+, Edge 121+).
Stack
SvelteKit 5 (Svelte runes) with PandaCSS, Ark UI, and Comlink for worker communication. Hosted on Cloudflare Pages as a fully static SPA.
Development
bun install
bun run dev
Model weights go in models/ (git-ignored). See src/lib/inference/models.ts for the expected directory structure.
bun run check # type-check
bun run lint # eslint
bun run format # biome
bun run build # production build
Keyboard shortcuts
| Key | Action |
|---|---|
P |
Point mode |
B |
Box mode |
Ctrl+Z |
Undo |
Ctrl+Shift+Z |
Redo |
Escape |
Clear prompts |
D |
Download mask |
Shift+D |
Download cutout |
? |
Show shortcut help |
