Compatibility
Browser support
Supported browsers, WebGPU acceleration, and the single-threaded WASM fallback.
Browser compatibility table
| Browser | Support level | Inference backend | Notes |
|---|---|---|---|
| Chrome 94+ | Full | WebGPU | Best performance |
| Edge 94+ | Full | WebGPU | Same engine as Chrome |
| Opera 80+ | Full | WebGPU | Same engine as Chrome |
| Firefox 90+ | Good | WebGPU or WASM | Backend depends on the browser and adapter detected |
| Safari 16.4+ | Good | WASM (varies) | WebGPU available in Safari 18+; service workers work |
| iOS Safari 16+ | Supported | WASM | Slower; install from Safari only |
| iOS Safari < 16 | Limited | — | Service workers not available; app warns on load |
What WebGPU provides
WebGPU allows the AI model to run on your device's GPU instead of the CPU. This makes inference significantly faster:
| Backend | Typical inference time |
|---|---|
| WebGPU (discrete GPU) | 1–3 seconds |
| WebGPU (integrated GPU) | 3–6 seconds |
| Single-threaded WASM | 20–60 seconds |
The quality of the output is the same regardless of backend — only the speed changes.
Why the WASM fallback is single-threaded
NSS pins ONNX Runtime Web to one CPU thread. During regression testing, the multi-threaded heap caused out-of-memory failures on large segmentation models. Cross-origin isolation is still applied to the two full editors as a privacy boundary, but SharedArrayBuffer availability does not change the inference backend today.
Checking your backend
The inference backend badge appears near the top of the upload zone:
- WebGPU — running on your GPU
- WASM (single) — CPU, single-threaded
Firefox notes
The site checks for a healthy hardware WebGPU adapter instead of assuming support from the browser name. When no suitable adapter is available, Firefox uses the same single-threaded WASM fallback as other browsers; output quality is unchanged, but processing takes longer.
Safari notes
Safari 16.4+ supports service workers and most PWA features needed for offline operation. Safari 18+ adds WebGPU support. If you're on macOS Sonoma or later with Safari 18, you should see the WebGPU badge.
Recommended setup for best performance
- Use Chrome or Edge on desktop
- Make sure your GPU drivers are up to date
- Don't run NSS in a private/incognito window (model caching is restricted)
Related
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