Tool
Lock PDF
Password protect any PDF in seconds. Set a password — anyone trying to open the file will need it.
Drop a PDF here, or click to browse
Lock a PDF in three steps
No software to install. Works in any browser, on any device.
Upload your PDF
Drop or click to upload the PDF you want to protect.
Set a password
Enter and confirm a strong password for the file.
Download the locked PDF
The encrypted PDF downloads instantly — nothing is uploaded to a server.
Password protection
Password protection
Anyone opening the file is prompted for the password first.
100% private
Password and encryption run in your browser using pdf-lib. Nothing sent to a server.
Standard encryption
AES-128 compatible with Adobe Reader and all major PDF viewers.
About PDF Password Protection
Locking a PDF adds 128-bit AES encryption to the file. When someone tries to open the document in any PDF reader — Adobe Acrobat, Preview, Chrome, or any other viewer — they will be prompted for the password before the contents are displayed.
This is useful for sending sensitive documents by email, sharing PDFs on shared drives, submitting forms that contain private information, or any situation where you want to control who can read the file.
The encryption runs entirely in your browser using pdf-lib. Your PDF is never uploaded to a server. Choose a strong password — the longer and more random it is, the harder it is to crack. Do not forget it: if you lose the password, the file cannot be opened.
Password strength matters. A short dictionary word can be cracked in seconds; a random 16-character string combining letters, numbers and symbols would take years. Use the Password Generator to create a strong one. After downloading the locked file, open it in your PDF reader to confirm the password works before sending to anyone.
Need to remove a password instead? Unlock PDF · Merge PDF · Compress PDF
More PDF tools
Frequently Asked Questions
What if I forget the password?
No recovery option exists. Store the password in a password manager — if lost, the file is permanently inaccessible through normal means.
What encryption is used?
AES-128 via pdf-lib, compatible with all modern PDF viewers.
Can I allow opening but prevent editing?
This tool sets an open password. Restricting editing separately requires a more advanced tool like Adobe Acrobat.
Does the password prevent printing?
This applies an open password only. Once unlocked, the recipient can view and print. Restricting those actions requires additional permission flags.