How it works

What normally happens

When you use a typical online file tool, your document is uploaded to that company's server, processed there, and the result is sent back. The file sits on a machine you don't control, for a period you can't verify, alongside everyone else's. Most of these services are honest and delete things on schedule. But "honest and on schedule" is a policy, and policies change, get breached, or get acquired.

For a holiday photo, none of that matters. For a signed contract, a payroll export, a medical form, or a spreadsheet of customer email addresses, it's a disclosure you probably didn't intend to make.

What happens here instead

Cleanroom is a static website. It's a set of HTML, CSS and JavaScript files served from a CDN — the same kind of thing that serves an image. There is no application server, no database, and no upload endpoint. Not "we don't use it", but there isn't one.

When you choose a file, your browser reads it into its own memory using an ordinary file input, exactly as a desktop program would. The JavaScript that splits your CSV or merges your PDF is already on your machine — it arrived with the page. It does the work locally and hands the result back to you as a download. At no point is there a network request carrying your data, because there is no address to send it to.

How to verify it — about thirty seconds

Don't take this on trust. There are three checks and all of them are quick.

1. Watch the network. Press F12 to open your browser's developer tools and switch to the Network tab. Now use any tool on this site. You'll see the page and its scripts load, and then nothing further. Your file doesn't appear because it doesn't move.
2. Pull the plug. Load a tool page, then turn off your Wi-Fi or unplug the network. Now use the tool. It works perfectly, because everything it needs is already on your computer. A site that uploaded your file could not do this.
3. Read the security policy. In developer tools, look at the response headers for this page and find Content-Security-Policy. It contains connect-src 'none'. That instruction forbids this page from opening any network connection at all — no upload, no background request, nothing. Your browser enforces it, not us.

That third one is the part we'd point at first. Everything else on this page is a description of how the site is built, which you'd have to take our word for. The security policy is a rule your own browser applies to us, and it's visible in two clicks. A site that uploads your files could not ship that header without breaking itself.

What this means in practice

Because processing costs us nothing, there's nothing to ration. No daily limits, no queue, no watermark on your document, no account to create, and no file size cap beyond what your own machine can hold in memory. The usual reasons those restrictions exist — bandwidth and CPU on someone else's server — don't apply.

It also means there are things Cleanroom genuinely can't do. Anything needing serious compute or a big model behind it — high-volume OCR, for instance — isn't a good fit for a browser tab, and we'd rather say so than quietly build a server and keep the slogan.

What we collect

Nothing about your files, because we never receive them. See the privacy page for the full detail on what the site itself records, which is close to nothing and will always be disclosed there.