Maher PDF

Protect a PDF with a password

Protect PDF (shown as Lock PDF in the tool list) encrypts a document so it can only be opened by someone who knows the password. On this site it uses AES-256, the strongest encryption method in the PDF standard, and it is supported by all modern PDF readers.

Choose a PDF to protect Accepts: One PDF file. Free, no sign-up.

Your files are processed inside this browser tab and are not uploaded to Maher PDF. Please read the Privacy Policy before working with sensitive documents.

This is real encryption, not a cosmetic lock: without the password, the contents of the file can't be read. That also means there is no way to recover the file if you forget the password, so store it somewhere safe.

How to use Protect PDF

  1. Tap Choose a PDF to protect and pick the file.
  2. Type a password into the password field. Use something long and hard to guess.
  3. Tap Run. A new file ending in _locked.pdf downloads.
  4. Open it once to confirm the password works before you send it.

Key features

  • AES-256 encryption on secure (HTTPS) connections.
  • Password and file never leave your browser.
  • Compatible with Adobe Acrobat, browser viewers, and phone PDF apps.

Supported files

Input: one PDF. Output: an encrypted PDF that requires the password to open.

Privacy and security

Encryption happens in this tab. Maher PDF never receives or stores your password, which is exactly why it can't help you recover it.

Common problems

I forgot the password.
It can't be recovered or reset. If you still have the unprotected original, protect it again with a new password.
The recipient can't open the file.
Make sure they are typing the password exactly, including capital letters. Very old PDF readers may not support AES-256; ask them to use a current reader or browser.

Tips

  • Send the password through a different channel than the file, for example the file by email and the password by phone or text.
  • Learn more in the PDF security guide.

Frequently asked questions

How strong is the encryption?

On this site the tool uses AES-256, the strongest method defined for PDF. Real-world security also depends on choosing a long, unpredictable password.

Can you recover my password?

No. The password never reaches Maher PDF, so nobody here can see or reset it.

Does protecting a PDF stop copying or printing?

This tool sets an open password. Anyone who has the password can open the file and do what their PDF reader allows.

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