katlab tools/protect-pdf support on Ko-fi

Protect PDF · add a password

Encrypt a PDF with an open password, and optionally block printing, copying or editing. AES-256, the same encryption Acrobat uses, done entirely in your browser.

The PDF and your passwords stay on your device. Nothing is uploaded.
12+ characters or four random words. There is no way to recover a forgotten password. Need one? Try the password generator.
Restrict printing, copying and editing (everything allowed)

Restrictions are respected by Acrobat, Preview, Chrome and other mainstream readers, but they are not encryption: anyone who can open the file can strip them with free tools, including ours. Treat them as a clear signal, and rely on the open password for privacy.

Lets you lift the restrictions later in Acrobat. Must differ from the open password, otherwise anyone who can open the file gets full rights.
AES-256 opens in Acrobat X and later and every current reader.
no file

How to password-protect a PDF (free)

  1. Drop your PDF onto the box above.
  2. Type a password to open the file, twice. Leave it empty if you only want to restrict printing or copying.
  3. Optionally open Restrict printing, copying and editing and untick what readers should not allow.
  4. Click Protect PDF and save the protected copy. Keep the original somewhere safe until you have checked the new file opens.

Open password vs. restrictions

An open password (user password) encrypts every page, image and attachment, so the file cannot be read at all without it. With AES-256 and a strong password this is real protection: nobody, including us, can open the file without the password.

Restrictions (owner or permissions password) leave the file readable but ask the reader app to block printing, copying, editing, form filling or comments. Readers honour them, but removing them takes seconds with free software, so they are a courtesy lock, not security. The Unlock PDF tool does exactly that for files you are allowed to use.

Which encryption should I choose?

AES-256 is the current PDF standard (PDF 2.0, Acrobat X and later). It opens in Acrobat, macOS and iOS Preview, Chrome, Edge, Firefox, Android readers and LibreOffice. Pick AES-128 only when the file must open in readers older than about 2010. Weak RC4 encryption is not offered.

Private by design

The tool ships QPDF compiled to WebAssembly and runs inside your browser tab. Your PDF and the passwords you type never leave your device, which matters because the documents people protect are usually the sensitive ones: contracts, payslips, medical records, tax returns.

Forgot the password?

There is no recovery and no backdoor. Store the password in a password manager, or keep the unprotected original in a safe place.

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