Koutuxia removes the background from a photo and hands you a transparent PNG. The free path runs BiRefNet-lite in the browser: a 47 MB int8 model downloaded once from a CDN and cached, then executed through WebGPU where the device supports it and WASM SIMD where it does not, at a smaller input resolution on weaker hardware. A paid path sends the image to a cloud model instead, for finer edges, higher resolution and batch jobs. Around the cutout you also get a one-click background colour swap for red, blue and white, a photo restoration mode, and direct export to transparent PNG. The browser-side tools are free and need no signup, and the site works from mainland China without a proxy.