PDF Protect
Free online PDF Protect. No sign-up needed, and it runs in your browser.
Add a password to a PDF so nobody can open it without it. AES-256 encryption, with optional limits on printing, copying and editing.
Limits and encryption (optional)
About PDF Protect
Adds a password that anyone must type before the PDF will open, which suits payslips, contracts, medical letters or client reports sent by email. The file is encrypted with AES-256 by default, with AES-128 kept for very old PDF readers. You can also block printing, copying or editing, and set a separate permissions password so that only you can change those limits later.
How to use PDF Protect
- Click Browse and choose your PDF. If it's already protected, type it in Current password of this PDF.
- Type a New password, then Type it again; the strength meter shows Weak, OK or Strong.
- Open Limits and encryption (optional) to block printing, copying or editing and set a Permissions password.
- Keep AES-256 (recommended), click Protect PDF, then click Download protected PDF to save the copy.
How your data is handled
Your PDF is encrypted in your browser and never uploaded. The passwords you type are used only on your device and aren't sent or saved, so keep a note of them yourself.
Limits and accuracy
- A lost password can't be recovered, so keep the original file or store the password safely.
- Printing and copying limits are honoured by most PDF readers, but some ignore them.
- Any digital signature in the PDF stops being valid once the file is re-encrypted.
- The open password needs at least 4 characters; 12 or more is far safer.
Questions and answers
How strong is AES-256 protection?
AES-256 is a modern encryption standard, and the contents can't be read without the password. In practice the password is the weak point, so use a long one: 12 or more characters, or several random words.
What happens if I forget the password?
The file can't be opened, and nobody, including this site, can recover the password for you. Keep a copy of the original PDF, or store the password in a password manager, before you send the protected copy.
What do the printing, copying and editing limits do?
They're extra rules for anyone who opens the file. Block editing also stops comments and moving pages, while form filling stays allowed. Most PDF readers respect these limits, but not all, so don't rely on them for real secrecy.
What is the Permissions password for?
It's a second password that gives full access, so you can lift the limits later while people with only the open password can't. It must be different from the open password. If you leave it empty, a random one is used, so the limits can't be changed with a password afterwards.
Is my PDF uploaded to add the password?
No. The file is encrypted by your browser on your device, and neither the PDF nor the passwords are sent to a server or stored. The encryption library loads from our site the first time.