PDF Tower

Your file stays on your device

PDF Tower processes PDFs inside your web browser. This page explains what that means, what we do receive, and how you can check it.

How it works

  1. Your browser loads PDF Tower's pages and its PDF engine from pdftower.com, like any website.
  2. When you choose a file, the browser reads it into the memory of that tab. The file is not sent anywhere.
  3. The engine, compiled to WebAssembly, fills, edits, merges or compresses the file in that same tab.
  4. When you save, the browser writes the new file to your device as a download.

When you open an official form, PDF Tower loads the blank PDF through pdftower.com and checks it against the issuer's file we verified. The blank is the same for everyone. What you type into it stays in the tab.

What we never receive

  • The contents of your documents.
  • What you type into a form, your signature, or your initials.
  • The files PDF Tower creates for you.

What we do receive

  • Ordinary web requests for our pages, scripts and images, which reach our hosting provider (Cloudflare) like any website visit.
  • If you buy a plan: your email address and subscription status. Payments are handled by Stripe; we never see your card number.

Pages that open your files load nothing from analytics or advertising services.

Check it yourself

  1. Open your browser's developer tools and select the Network tab.
  2. Open a PDF in any PDF Tower tool, fill or change it, and save it.
  3. Look at the requests. None of them carries your file or what you typed.

What on-device processing does not protect against

  • Malware or untrusted browser extensions on your own device can read what is on your screen.
  • On a shared computer, the files you save stay in that computer's downloads folder.
  • Once you send a saved file to someone, it is in their hands.

The engine

The PDF engine is based on PdfCraft by the ArtCraft team, an open-source project licensed under MIT or Apache-2.0.