Add a password to a PDF with strong AES-256 encryption, so only people with the password can open it. Runs entirely in your browser.
Drop a PDF, set a password, and download an encrypted copy.
Files are processed in your browser and never uploaded.
How to use the Protect PDF
Drop a PDF. It is read in your browser and never uploaded.
Choose a password and confirm it.
Download an encrypted copy that asks for the password to open.
Frequently asked questions
The PDF is encrypted with AES-256, the strongest standard PDF encryption. Anyone without the password cannot open the contents.
No. The encryption happens entirely in your browser, so the document and the password never leave your device.
Yes. The result is a standard encrypted PDF that any modern reader (Acrobat, Preview, browsers and phones) opens after asking for the password.
There is no recovery. The encryption is real, so keep the password safe. Without it, the PDF cannot be opened.
This tool adds a password to protect a PDF. The PDF unlock tool removes a password from a file you can already open, giving you an unprotected copy.
A PDF protector that adds a password to a document with AES-256 encryption, so only people who know the password can open it. The text and quality are preserved exactly.
Password-protecting a PDF is the right move before sending anything sensitive by email or a shared link, a contract, a bank statement, a payslip, an ID, where you do not want anyone who gets the file to be able to read it.
The encryption is real, not a flimsy restriction. AES-256 is the strongest standard PDF encryption, so without the password the contents cannot be read, even by someone who has the file.
The result is a standard encrypted PDF, so it opens in any modern reader, Acrobat, Preview, browsers and phones, after prompting for the password. There is nothing proprietary about it.
Protecting is lossless: it does not rebuild or rasterize the document, so all text, images and fonts stay exactly as they were and the file remains searchable once unlocked.
It runs entirely in your browser using QPDF compiled to WebAssembly, so your PDF and the password never leave your device. The companion PDF unlock tool removes a password when you know it.
Embed this tool
Add this tool to your own website. Copy the snippet below; it stays up to date automatically.
<iframe src="https://monu.tools/embed/en/pdf-protect" width="100%" height="640" style="border:1px solid #e5e5e5;border-radius:12px;max-width:680px" loading="lazy" title="Monu Tools"></iframe>Related tools
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