How Upscale works
Upscale is a free, private AI image upscaler. It runs entirely in your browser as an installable PWA, enlarging photos 2× or 4× with a super-resolution model (ONNX) compiled to WebAssembly. Your image never leaves your device.
Everything happens on your device
There is no server and no backend. When you load an image, your browser runs the AI model locally and produces a higher-resolution image. Nothing you upload is ever sent over the network. The site's Content-Security-Policy (connect-src 'self', plus only the public model CDN) even restricts which hosts the page may contact, so the privacy guarantee is enforced by the browser itself.
The only network access is the model
On the first run, Upscale fetches the public super-resolution model from the Hugging Face CDN (a small ONNX file — about 1.7 MB for 2× and 2.5 MB for 4×). That download is a plain GET of a generic public file — your image is never uploaded to it. Once downloaded, the bytes are cached (Cache Storage + the service worker), so the tool keeps working with no connection at all.
WebGPU when you have it, WebAssembly otherwise
When your browser supports WebGPU, the model runs on your graphics card for a faster path. If not, it falls back to CPU-based WebAssembly, which works everywhere. Either way, the processing stays on your device.
Why is the source size limited?
Super-resolution multiplies pixels, so the binding limit is the output size. To keep the in-browser run fast and memory-safe on every device,Upscale caps the output to roughly 3000 px on the long edge: 2× accepts sources up to ~1500 px and 4× up to ~750 px (larger sources are gently downsampled first). For most images you want to enlarge — which are already small — this is a non-issue.
Offline-capable PWA
Install Upscale to your home screen or desktop. A service worker caches the app shell and the AI model, so upscaling keeps working with no internet connection once the model has loaded once.
No ads, no tracking, no account
There is no signup. This build ships with zero third-party scripts and a strict privacy policy. If monetization is added later, it will be environment-gated and off by default — the on-device privacy promise for your images is never traded away.