1. Your image stays on your device
When you drag a photo into the tool, your browser holds it in memory as a temporary object — the same way it holds an attachment you've selected in Gmail before hitting send. Crucially, CutoutKit never transmits that file anywhere. There is no upload step, no signed URL, no server bucket. If you switch to airplane mode after the tool has loaded once, it still works.
2. A small AI model loads once
The first time you use CutoutKit, your browser downloads a compact image-segmentation model (around 30 MB) and stores it in its cache. The model is based on the same family of neural networks used by professional photo editors — it has been trained on millions of images to recognize where a subject ends and a background begins. After that first download, the model lives on your device and loads almost instantly on subsequent visits.
3. WebAssembly does the heavy lifting
Modern browsers can run high-performance code via WebAssembly, a technology that lets compiled programs run directly inside your tab at near-native speed. CutoutKit uses WebAssembly to execute the segmentation model, which is what makes it fast enough to be practical without a server. On a recent laptop or phone, a typical photo finishes in under 10 seconds.
4. The result is a transparent PNG
Once the model has decided which pixels belong to the subject, CutoutKit produces a new image with the background pixels made fully transparent. PNG is the universal format for transparent images — it's supported by every design tool, slide editor, and social platform you're likely to use. The download button hands you that PNG directly; no copy-pasting and no temporary URL on someone else's server.
A note on quality
No background remover, online or offline, is perfect on every image. Tricky cases — fine hair against a busy background, transparent objects like glass, or low-contrast subjects — sometimes need manual touch-ups in a tool like Photoshop, GIMP, or Photopea. CutoutKit aims to give you a great starting point for 90% of photos, not to replace a professional retoucher for the remaining 10%.