QRix
Remove whatever is behind the subject and download a PNG with real transparency, ready to place on any colour.
Result will appear here
Transparency is a property of the file, not something you can fake by painting the background white. A PNG stores, for every pixel, how opaque it is — which is why a transparent PNG dropped onto a blue slide shows blue behind the subject, while a white JPG shows a white box. That is the entire difference, and it explains most of the confusion around this: JPG has no way to record transparency at all, so anything exported as JPG loses it permanently. Export as PNG and it survives. The result here downloads as a PNG whether you keep the background transparent or replace it with a colour. If you need the smaller file that JPG gives you, convert afterwards — but only once the image is going somewhere with a fixed background, because the transparency will not survive the trip.
Most image viewers paint white behind transparency. Place it on a coloured background — a slide, a page, a chat — and you will see the transparency is really there.
No. The format has no channel for it. Saving a transparent image as JPG replaces the transparency with a solid colour, usually white or black.
No. The file you download is the image, produced by your own browser.
The limit is your device's memory, since the work happens there. Very large photos are slower on a phone than on a laptop.
It's free, private and works right in your browser — no signup, no watermark.