Add a password and permission restrictions to a PDF right in your browser — set an open password, an owner password, and control printing, copying, and editing. Nothing, including your passwords, is ever uploaded to a server.
Everything happens in your browser — your PDF and passwords are never uploaded to a server.
Drag and drop a PDF file here, or click below to browse.
Not every PDF is meant for unrestricted access. A contract shouldn't be casually editable after both parties have signed it. An internal report might need to circulate freely for reading but shouldn't be easy to copy into a competitor's document. A personal or financial document you're emailing deserves at least a basic password barrier against a wrong recipient or a compromised inbox. Protection gives you a standard, widely-supported way to add exactly that kind of barrier, using a mechanism every PDF reader already understands rather than a proprietary wrapper only your own tool can open.
This comes up constantly in ordinary work: password-gating a document before emailing it to a client, distributing a read-only reference PDF that shouldn't be edited or redistributed piecemeal, or simply adding a password to a personal document — tax records, medical paperwork, financial statements — before storing it somewhere less trusted than your own device.
When you protect a PDF, this tool derives a cryptographic key from your chosen passwords using the PDF specification's published key-derivation algorithm, then uses that key to encrypt the document's text, images, form data, and other content throughout the file. It also computes two special values — often called O and U — that let any standards-compliant PDF reader verify a password is correct without ever storing the password itself anywhere in the file; a reader checks a candidate password by running the same derivation and comparing the result, not by comparing plaintext passwords.
Alongside the password mechanism, a permissions value gets embedded in the file recording exactly which operations (printing, copying, editing) are allowed. Every compliant PDF viewer reads and respects this value once the file is decrypted, which is what makes permission restrictions work consistently across different software rather than being tied to any one application's proprietary behavior.
Think of the user password and the permission toggles as two independent layers you can combine freely. A user password alone (with all permissions left allowed) is the simplest setup: nobody can even open the file without the password, but once they do, they can do anything with it. An owner password alone, with some permissions turned off, is the opposite: anyone can open and read the file, but printing, copying, or editing are restricted for everyone except whoever knows the owner password. Setting both together — a user password to gate access, an owner password with restricted permissions to limit what's allowed even for people you've given the open password to — gives you the most granular control, useful for something like a confidential draft you're sharing with a reviewer who should be able to read it but not print or forward its contents.
It's worth being realistic about what PDF protection actually accomplishes: it's a well-understood, broadly respected convention that stops casual access, printing, or copying by anyone using standard PDF software as intended. It is not equivalent to strong, modern encryption protecting a secret against a determined attacker with specialized tools — the underlying cipher this tool uses (like the classic security handler in general) is considered comparatively weak by current cryptographic standards. For everyday document control — keeping honest people honest, adding a reasonable barrier to accidental or casual access, satisfying an organization's basic 'documents must be password protected before emailing' policy — it's exactly the right tool. For protecting something where a sophisticated, motivated attacker is a real threat, treat PDF password protection as one layer among several, not a complete solution on its own.
Protect PDF adds password and permission restrictions. These related PDF tools cover the rest of a typical PDF workflow — removing protection, and combining or converting documents.