Why browser-only

ClipBrook does not upload your images, and not as a policy: there is no server that could receive them. The site is a folder of static files. Your browser downloads the pages and the cutting engine, and the engine then runs in worker threads on your own computer. When you drop a render, the pixels go from your disk into the browser tab, through the cut, and back out as a PNG download. They are never inside a network request.

How to check it yourself

1. Open your browser’s developer tools and go to the Network panel. In Chrome, Edge and Firefox that is F12; in Safari, turn on the Develop menu in Settings first.
2. Reload ClipBrook with the panel recording. You will see the site loading its own files: the page, the fonts, the scripts, and the three demo renders if you press the demo button.
3. Clear the list, then drop a folder of your own renders in and let them cut.
4. Nothing new appears in the list. Drop an 80 MB file and it still does not move.

The engine is open source under the AGPL, so once the repository is public you can read the code that does this as well; the open-source page has the details.

What running on your own computer means in practice

Your file is cut at the size it arrived at. Matting models work on a fixed input size and the mask is scaled back up afterwards: the library measured on the comparison page hands its model a 1024 by 1024 copy whatever you send it. ClipBrook cuts a 4096 px render at 4096 px. The comparison page shows what the two approaches do to the same renders.

There is no meter. Cutting that costs the site nothing needs no account, no credit balance and no monthly cap, and ClipBrook has none of them.

Work that should not travel does not travel. Client art before the client has seen it, or a design for a product nobody has announced yet, stays on the machine it was already on.

The trade

Your computer does the work, so your computer sets the pace. A ten-year-old laptop is slower than a rented datacenter GPU, and a phone runs out of memory long before it runs out of time. ClipBrook takes images up to 8192 px on a side and 80 MB per file, and it checks the memory a file will need before it starts, so it declines a file rather than crashing on it. A phone will refuse larger images than a desktop will. How long one cut takes depends on the size of the image and on the computer doing it.

What the site stores

Your slider positions, backdrop choice and export settings go into your browser’s localStorage, so they are still set the next time you visit. That data describes the controls, never your images, and it never leaves your computer. The privacy page lists all of it.

What it does not do

It does not work on photographs. A photo has no key color to remove. ClipBrook is a chroma keyer: it measures one flat background color and solves each edge pixel against it, rather than guessing where a subject ends. For a photograph there is nothing to measure, and a hosted matting tool is the right choice.

If you generate the images yourself, the prompt guide covers which key color to pick for your subject, and the prompt wording that keeps the background flat.