Finding faces for you
Press Find faces and every face the tool spots is covered straight away. Where the browser has a built-in face detector it is used; otherwise a small face detection model runs on this device, downloaded once on first use. No detector catches every face, especially tiny, turned-away or partly hidden ones, so always look over the photo before you save it and cover anything left with the box or brush. If neither detector can run in your browser, the page says so and the hand tools still work.
Pixelate, blur or solid
Pixelate replaces an area with large blocks of colour and is hard to undo at higher strengths. Blur gives a softer look that suits faces in the background. Solid paints a plain block, which is the right choice for names, addresses, card numbers and number plates, where even a few readable letters matter. The effect is baked into the pixels of the saved photo; it is not a layer anyone can remove.
Hidden details are left out
Photos from phones and cameras often carry the time, the device and the exact location where they were taken. The saved copy is drawn fresh from the pixels, so none of that comes along. Your photo is never uploaded: the detection, the blurring and the saving all happen in this browser tab.