Compatibility
Browser support
Which browsers are supported and what features require WebGPU or SharedArrayBuffer.
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 | Multi-threaded WASM | No WebGPU (as of 2026); slower but same quality |
| 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 |
| Multi-threaded WASM | 10–20 seconds |
| Single-threaded WASM | 20–60 seconds |
The quality of the output is the same regardless of backend — only the speed changes.
SharedArrayBuffer
Multi-threaded WASM (the fallback when WebGPU isn't available) requires SharedArrayBuffer. This in turn requires the page to be served with:
Cross-Origin-Opener-Policy: same-originCross-Origin-Embedder-Policy: require-corp
NSS sets both headers correctly. However, some browser extensions or corporate proxies strip these headers. If you see a "SharedArrayBuffer not available" warning, single-threaded WASM is used as a further fallback.
Checking your backend
The inference backend badge appears near the top of the upload zone:
- WebGPU — running on your GPU
- WASM (multi) — CPU, multi-threaded
- WASM (single) — CPU, single-threaded
Firefox notes
Firefox does not support WebGPU in standard builds. Mozilla has WebGPU under development; once stable and enabled by default, Firefox will get GPU acceleration automatically. In the meantime, Firefox users get multi-threaded WASM inference — slower than WebGPU but still correct output.
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)