Password Protect PDF
Add real AES encryption to a PDF so only someone with the password can open it — with a built-in strength meter, a secure password generator, and fine-grained control over printing, copying, and editing.
Drop a PDF here, or click to browse
How PDF password protection works
This tool applies standard PDF encryption using AES, the algorithm built into the PDF 2.0 specification for securing documents. Under the hood it uses a WebAssembly build of QPDF, a mature, widely trusted open-source PDF library that's powered PDF encryption and repair tools for years — compiled to run entirely inside your browser instead of on a server.
You set a password required to open the file, and optionally a separate owner password that controls permissions like printing and copying independently of the open password. Choose 128-bit or 256-bit AES — 256-bit is the stronger, more modern default used by banks and government agencies for sensitive documents, while 128-bit remains widely compatible with older PDF readers. Because everything runs locally, your password is never transmitted anywhere, and neither is the document you're protecting — that holds true on a phone or tablet just as much as on a desktop.
Beyond the open password, you can independently allow or restrict four things a reader might otherwise do once the file is open: printing, copying text and images, commenting or filling in form fields, and editing or reassembling pages. Not every PDF reader honors every restriction identically, but every standard-compliant reader will still require the open password before showing any content at all.
Common use cases
- Protecting financial statements or tax documents before emailing them
- Restricting who can open a contract or legal document, and locking editing once it's signed
- Adding a password to a document before uploading it to shared cloud storage
- Sharing a form that recipients can fill in and comment on, but not print or copy from
- Preventing casual copying of proprietary or confidential content
Keep in mind: PDF password protection deters casual access but isn't unbreakable against a determined, well-resourced attacker with enough time and computing power. For most personal and business use, though, it's a real and meaningful layer of protection recognized by every standard PDF reader — and it's only as strong as the password you choose, which is why the strength meter and generator are built directly into this tool.
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Password Protect PDF — frequently asked questions
It's real AES encryption (128-bit or 256-bit, your choice) using the standard PDF encryption format defined by the PDF 2.0 specification — not a cosmetic restriction. A PDF protected here can't be opened by any reader without the correct password.
Yes. Since this uses the standard PDF encryption format, any compliant PDF reader — Adobe Acrobat, Preview, browser PDF viewers, mobile PDF apps — will prompt for the password you set before showing the content.
There's no recovery option — that's the point of real encryption. Use the password generator and copy button on this page to save a strong password somewhere safe (like a password manager) before you share the protected file.
No. Encryption happens entirely in your browser using a WebAssembly build of QPDF — nothing is uploaded, and your password never leaves your device.
The user password controls opening the file. The optional owner password controls permissions like printing and copying independently — someone can open the file with the user password but can't override your permission restrictions without the owner password. Most people can leave it blank; the tool then uses your open password for both.
Yes. Open the Permissions section to allow or restrict printing, copying text and images, commenting and filling in forms, and editing or reassembling pages — independently of each other. All four are allowed by default.
At least 12 characters, mixing upper and lower case, numbers, and symbols — and unique to this file rather than reused elsewhere. The strength meter below the password field gives instant feedback, or tap "Generate a strong password" for a random one built with the browser's cryptographic random number generator.
Yes. The tool, the strength meter, and the permissions toggles all work with touch on mobile and tablet browsers, not just desktop — there's nothing to install.
The tool checks for this as soon as you add the file and tells you right away, rather than failing partway through — remove the existing password first with the Unlock PDF tool, then protect it here with a new one.