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Protect PDF

Add a password to a PDF so only people who know it can open the file, with optional limits on printing, copying and editing. Uses AES-256 encryption, and nothing is uploaded.

  • Free
  • No sign-up
  • Runs in your browser

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Guide

What protecting a PDF does

Protecting a PDF locks it with a password. Anyone who tries to open the file is asked for the password, and without it the pages can't be read at all.

This tool uses AES-256 encryption, the standard set by PDF 2.0 and the same strength Adobe Acrobat uses. The contents of the file are scrambled with a key that only the password can unlock, so this is real protection, not just a setting that a viewer can choose to ignore.

You can also limit what people can do once the file is open: printing, copying text and editing. Most PDF readers respect those limits, but some apps ignore them, so treat them as a polite request. The password itself always applies.

When to password-protect a PDF

Lock a PDF whenever it holds information you wouldn't want a stranger to read if the file ended up in the wrong inbox:

  • payslips, salary letters and tax documents
  • contracts, agreements and quotations
  • bank statements and invoices
  • ID scans, certificates and medical reports
  • exam papers or reports you send before release

Send the password a different way from the file, for example the PDF by email and the password by WhatsApp or a phone call. If both travel together, anyone who gets the email gets both.

How to lock a PDF with a password

  1. Drag a PDF onto the upload area, or click to choose it.
  2. Type a password, then type it again in Repeat password. A bar shows how strong it is.
  3. Optionally untick Print, Copy text or Edit to limit what people can do after opening it.
  4. Click Lock PDF, then Download PDF. The file is saved with -protected added to its name.

The PDF and your password stay in your browser: nothing is uploaded to a server.

Choosing a good password, and what to know

Encryption is only as strong as the password. A short or common one, such as 123456 or a name, can be guessed by software that tries millions of combinations. Use at least 10 to 14 characters, or a few random words together, such as river-lamp-orange-42. The Password Generator can make one for you.

There is no way to recover a forgotten password, so keep your original, unprotected PDF somewhere safe.

If the PDF is already password-protected, remove the old password with Unlock PDF first, then lock it again with the new one.

Frequently asked questions

How strong is the protection?

The PDF is encrypted with AES-256, the PDF 2.0 standard. With a long password it can't realistically be broken; with a short one it can be guessed, so choose at least 10 characters.

Will the locked PDF open on phones and in Adobe Reader?

Yes. Adobe Acrobat and Reader, browsers like Chrome and Edge, and phone PDF apps all open AES-256 protected PDFs and ask for the password.

I forgot the password. Can you unlock it?

No. Without the password the file can't be opened, by this tool or anyone else. Keep the original, unprotected copy.

Is my PDF uploaded to lock it?

No. The encryption happens in your browser, so the file and the password never leave your device.