Protect a PDF with a password.

Encrypt your PDF with a password of your choice — right here in your browser. Nothing is uploaded, and the password never leaves your device.

Open your network tab while it runs: zero requests. Your document stays yours.

How to password-protect a PDF

Select your PDF — drag it in or pick it from your device. It is read locally — no upload ever happens.
Set a password — type it twice so a typo can't lock you out. Minimum four characters; longer is stronger.
Download the protected file — the encrypted PDF downloads instantly. Anyone opening it — in any PDF reader — will need the password.

Most online protectors upload your document to their servers before encrypting it — which is exactly the moment it's most exposed. This tool encrypts on your device instead. It runs on the same in-browser engine as our PDF merger, PDF splitter, and PDF to Markdown converter — the file never leaves your machine.

Protecting PDFs, honestly answered

01 Is my PDF or password uploaded anywhere?

No. The encryption runs entirely in your browser. Neither the file nor the password is ever sent over the network — you can watch the network tab while it runs.

02 How do I lock a PDF so others can't open it?

Set a password here and download the protected copy — every PDF reader (Adobe, Preview, Chrome) will demand the password before opening it. The encryption is standard PDF encryption, applied on your device.

03 What kind of protection is added?

Standard PDF encryption, the same mechanism desktop PDF apps use. Any PDF reader — Adobe, Preview, Chrome — will ask for the password before opening the file.

04 Can you recover my password if I forget it?

No — and that's the point. Because everything happens on your device, we never see the password and cannot recover it. Store it somewhere safe.

05 Is there a file size or page limit?

No hard limit. Since your own device does the work, very large files are limited only by your browser's memory.

06 Is this free?

Yes, completely. No account, no watermark, no daily quota.

Still something on your mind? Try it yourself — it's free

Ready to fall in love with PDFs again?

Free, no account — and your files never leave your device.

Try PDFLove AI — It's Free →

Coming soon · Premium

Take every tool offline — native apps for Mac, Windows, Linux, iOS & Android.

Every tool on this site, running natively on your device
Fully offline — files never even touch a browser tab
Batch-process whole folders of documents locally

The native apps will be a one-time paid upgrade when they launch — everything in the browser stays free, always.