How do I password protect a PDF?

Drop the PDF here, type a password twice, and press Protect PDF. Download the protected copy: anyone who opens it, in Adobe Reader, a browser or on a phone, has to type the password first.

How strong is the encryption?

AES-256 (PDF security revision 6), the strongest the PDF format has, supported by Adobe Acrobat and Reader 9 and later, Chrome, Edge, Firefox, macOS Preview, iPhone and Android. With a long password, the file can't realistically be opened without it.

What is the difference between the open password and permissions?

The open password encrypts the file: without it nobody can read it. Permissions (no printing, no copying, no editing) are rules PDF readers follow, protected by a separate owner password. They stop casual use, but anyone who can open the file can remove them, so use the open password for anything private.

Is my PDF or password uploaded?

No. The encryption runs in your browser on your device; the PDF and the password are never uploaded or stored. It is free, with no sign-up.

What if I forget the password?

It can't be recovered, by us or anyone else. Keep the password somewhere safe, and keep an unprotected original of the file.

Yes. Every tool is free to use, with no account and no credit card. The work runs on your device rather than on our servers, which is what keeps it free to run.

Are my files uploaded?

No. Your files are opened and processed inside your browser and are not sent to LibraTool. Some tools first download a processing engine or AI model to your browser; that download contains no data of yours.

Does it work on mobile?

Yes. It runs in current mobile browsers on iOS and Android, with nothing to install. Very large files can be slow or run out of memory on a phone, so use a computer for those.

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Free Password Protect PDF

Add a password to a PDF with AES-256 encryption, and optionally turn off printing, copying or editing. Runs in your browser; nothing is uploaded.

File size depends on your deviceFiles stay privateNo login requiredFree foreverNo watermarkAES-256Print / copy / edit permissions

Drop a PDF here to add a password, or click to choose

PDF · processed on your device

or press Ctrl+V to paste from your clipboard

Browse files

Your files never leave your device. All processing happens locally in your browser.

AES-256 encryption, the strongest the PDF format has. Free, no sign-up, your file and password stay on your device.

How It Works

Adds a password to a PDF with AES-256 encryption, the strongest the PDF format offers, in your browser. Optionally sets an owner password and turns off printing, copying or editing.

1
You choose a password
A strength hint shows how hard it would be to guess, and a random passphrase can be suggested.
2
Optional permissions
Turn off printing, copying text and images, or editing, protected by a separate owner password.
3
The file is encrypted
Every page, font and image is encrypted with AES-256 (PDF security revision 6) by qpdf, compiled to WebAssembly.
4
The result is verified
The new file must refuse to open without the password and open with it, with every page intact, before it is offered.

The PDF and the password never leave your device and are never stored.

Related Tools

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File Encryption (AES-256-GCM)

Encrypt any file with a password using AES-256-GCM and PBKDF2 (250,000 iterations). The .enc output opens only with the right password, and only this tool can decrypt it. Fully client-side — your file never leaves your device.

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Text Encryption

Encrypt and decrypt text with a password using strong AES-256-GCM. The password never leaves your browser. Share secrets safely.

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Video Watermark — Add Text or a Logo to a Video

Put your name, a copyright line or your logo on a video: pick a corner or the centre, or repeat it across the frame, set the size, opacity and angle, and download an MP4. Text works in any language. Runs in your browser; your video is not uploaded.