MSMuhammad Shahid

Free tool · runs in your browser

Protect PDF with a password

Add a password to a PDF with strong encryption, so only people who know it can open the file.

Quick answer

Choose a PDF, enter a password twice, and press Protect. The file is encrypted with AES-256, the strongest standard in the PDF format, so it cannot be opened without the password. You can also say whether printing, copying and editing are allowed. Encryption happens in your browser, so your file and password are never sent anywhere. A lost password cannot be recovered.

How to use it

  1. Choose a PDF. A file that is not already protected.
  2. Set a strong password. Enter it twice, then choose what readers may do.
  3. Download. Press Protect PDF and share the password separately from the file.

Example

A contract protected before being emailed:

Input

contract.pdf
Password: a long, random password
Allow printing: yes, Allow editing: no

Output

contract-protected.pdf
Encrypted with AES-256. It asks for the password when opened.

Common errors and how to fix them

The two passwords do not match
Retype them, or tick "Show password" to check for a typing mistake.
This PDF is password protected
It already has a password. Remove it with the Unlock PDF tool first.

Frequently asked questions

How secure is the protection?

AES-256 is very strong when paired with a strong password. A long, random password of 12 or more characters is what really protects the file, as short ones can be guessed.

What if I forget the password?

Nobody can recover it, including this site, as the password is never stored. Keep a copy of the original or store the password in a password manager.

Will all PDF readers open the file?

Yes for current versions of Adobe Reader, Chrome, Edge, Firefox and Apple Preview. Very old readers from before about 2009 may not support AES-256.

Are the printing and copying limits secure?

Treat them as polite requests. Well-behaved apps follow them, but some software ignores them. The opening password is the real protection.

Is my password sent to your server?

No. There is no server involved: the encryption runs in your browser.

How should I send the password?

Use a different channel from the file: email the PDF, then send the password by message or phone.

Can I change or remove the password later?

Yes. Remove it with the Unlock PDF tool, using the current password, then protect the file again with a new one.

Can I protect an already protected PDF?

Remove the current password first with the Unlock PDF tool.

What makes a good PDF password?

Long and random, 12 characters or more, and not used elsewhere. The password generator creates one for you.

Does protecting a PDF make it bigger?

Only slightly, because encryption adds very little data. To reduce the size, use Compress PDF before you add the password.

Sources

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By Muhammad Shahid. Last updated .