Your files never leave the room.
Put an image in and watch the readings. Nothing is uploaded, and the page says so by measuring itself rather than by promising.
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Nothing here is uploaded. Disconnect from the internet and the page keeps working.
The same engine pointed at a single conversion, with the settings already right and a page that says what that conversion actually costs you — including when it is a bad idea.
What makes this different from the others
Browser-based image tools are no longer rare, and “we don’t upload your files” has stopped being a distinction — a dozen sites now say it. So here is what is actually different, stated plainly enough that you can check each claim.
It reads and writes real folders
Most tools take files one at a time and hand back a ZIP you then have to unpack. On Chrome and Edge, NoUpload can open a folder, read every image inside it, and write the finished files straight back into a folder you choose. No zipping, no unpacking, no download tray. A server-based tool cannot offer this at all: the files would have to make a round trip first.
It decides per image, and shows its working
A logo and a holiday photograph want opposite treatment, so one quality slider applied to a whole folder is wrong for half of it. Auto mode looks at each image — how many distinct colours it holds, how much of it is unbroken flat colour, whether it has transparency — then encodes it two ways and keeps the smaller file. Every row tells you what it chose and what it beat, so the decision is auditable rather than magic.
The privacy claim is enforced, not promised
Every page is served with a Content-Security-Policy containing connect-src 'none'.
That is an instruction to your browser to refuse any network request this page attempts, whatever
the code says. There are no third-party scripts, no analytics, no web fonts loaded from anyone
else’s server — so nothing about your visit is reported anywhere, by anyone.
Honest about the limits
The encoders here are the ones built into your browser. Tools that ship WebAssembly builds of MozJPEG or AVIF can squeeze a few percent more out of the same picture, at the cost of a multi-megabyte download before you can do anything. That is a real trade and you should know which side of it you are on: this site loads in well under a second and starts working immediately.