Why your PDFs shouldn't have to leave your computer

Think about the last few PDFs you merged, signed or shrunk. A lease, a pay stub, a medical letter, a tax form, a copy of a driver's license. They are some of the most private documents people own, and they are exactly the ones that end up in a free online PDF tool five minutes before a deadline.

Most of those tools work the same way: your file is uploaded to the company's servers, processed there, and sent back. It usually works fine. But for the time it sits there, a copy of your document exists on a computer you know nothing about.

What happens when a file is uploaded

An upload is not a glance. The whole file is copied to a server, often in another state or country, and kept until the service deletes it. Reputable services delete files after an hour or two and say so. Even then, while it exists, your document is:

• stored on infrastructure run by the tool's company and, usually, by the cloud providers it rents from;
• reachable by anyone who breaks into those systems, or by an employee or contractor with the wrong kind of access;
• subject to that company's own policies, which can change, and the laws of wherever the server sits;
• copied twice more over the internet: once on the way up and once on the way back.

None of this means a particular service is careless. It means that every upload creates a copy you can't see, can't check and can't delete yourself. The safest copy of a private document is the one that never gets made.

The other way: the work happens in your browser

Modern browsers can run real document software. The same kind of code a desktop PDF program uses can be delivered as part of a web page (through a technology called WebAssembly) and run on your own computer or phone. When you use a tool built this way, the page loads once, you pick your file, and the processing happens on your device. The file is read from your disk, changed in your browser's memory, and saved back to your downloads folder.

That is how most of Filezuma works. Merging, splitting, compressing, rotating, signing, redacting, filling in forms, adding page numbers and watermarks, editing text, OCR and more all run in your browser. Your document is never sent to us, so there is no copy of it on our side to lose, leak or delete.

Why it is better, not just safer

• Nothing to trust. You don't have to take a retention policy on faith, because there is nothing retained.
• Faster with big files. A 40 MB scan does not have to travel to a server and back over your connection.
• Fine for client files. Accountants, lawyers, landlords and HR teams handle other people's documents. Keeping them on your own machine avoids handing them to another company at all.
• No account, no limits on the browser tools. They cost us nothing to run, so they are free to use as often as you like.

Check it yourself

You don't have to take our word for it. In Chrome, Edge or Firefox, open the developer tools (F12, or right-click and choose Inspect), go to the Network tab, and then use a tool such as Merge PDF. You will see the page's own files load, the sign-in service, an anonymous page-view count and, on free pages, ads; but no request that carries your document. The file is never in the list because it never leaves.

The honest exceptions

A few conversions need software that can't run in a browser yet: Word, Excel and PowerPoint to PDF, PDF to Word and PowerPoint, and web page to PDF. For those we use our own server, we say so on the page before you start, and the file is deleted as soon as the conversion is done. Every tool page shows a badge telling you which kind it is, and the privacy page has the details.

Sending a document for others to sign (Signzuma) is different by nature: the document has to be stored so the other people can open it. It is kept privately for you and deleted when you ask.