Protect a PDF with a password
Lock your PDF so it can only be opened with a password. The encryption happens on your device and the file is never uploaded.
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How to use Protect PDF
- Select the PDF you want to lock.
- Type a password and confirm it.
- Press Protect PDF and download the locked file.
A password stops other people from opening a PDF you email or share. This tool uses AES-256 encryption, the same standard used by modern PDF software, and the protection works in Adobe Reader, Chrome, Edge, Preview and most phone PDF apps.
Everything is done in your browser, so the PDF and your password are never sent to a server. Share the password through a different channel than the file, and keep a copy somewhere safe, because a forgotten password cannot be recovered.
When to use Protect PDF
- Send salary slips, bank statements or medical reports by email more safely.
- Share a contract or a quotation that only the client should open.
- Lock scanned copies of your ID documents before storing them in the cloud.
- Protect exam papers or answer keys until the right time.
Tips for the best result
- Use a long password of 12 or more characters, such as three unrelated words with a number.
- Send the password by a different route than the file, for example the file by email and the password by phone or SMS.
- Write the password down somewhere safe. A lost password cannot be recovered by us or anyone else.
- Make all your edits first. Merging, rotating and other changes need the file unlocked.
If something goes wrong
- The receiver says the password is wrong. Check the capital letters and look for a space at the start or end. Avoid letters outside English in the password.
- The file is refused. It may already have a password. Remove the old password first, then protect it again.
- An old PDF app cannot open the file. AES-256 needs a reasonably modern PDF reader. Ask the receiver to use Chrome, Edge, Adobe Reader or a current phone app.
Frequently asked questions
Is my PDF or my password uploaded?
No. The PDF is encrypted in your browser. Neither the file nor the password leaves your device.
How strong is the protection?
AES-256 encryption. The real strength depends on your password, so use 12 or more characters and avoid names or dates.
What if I forget the password?
The file cannot be recovered. Keep the password in a password manager.
Can I use letters from my own language in the password?
Use English letters, numbers and symbols only. Other characters may not work in every PDF reader.
Does it work on already protected PDFs?
No. Unlock the file first, then protect it again with a new password.
Can I stop printing or copying instead of opening?
This tool sets an open password, so nobody can view the file without it. Separate printing and copying limits are not offered.
Does protecting change the content?
No. The pages look the same once the password is entered.