Are the PDF and password uploaded?

No. qpdf runs as WebAssembly inside your browser, so neither the PDF nor the password leaves your device.

What's the difference between user and owner password?

The user password is required to open the PDF. The owner password is required to change the permissions (printing, copying, editing). Setting both is the most common pattern, but using one is fine too — if you only set one, the same value is used for the other internally.

Should I pick AES 256-bit or 128-bit?

Pick 256-bit unless you have a specific reason not to. It works with Acrobat 9 (2008) and every modern PDF viewer. Only fall back to 128-bit when you need to support Acrobat 7 / 8 era viewers.

Can I add a password to a PDF that's already encrypted?

Not directly. Unlock it first with the "PDF unlock" tool, then come back here to set a new password.

Does content stay intact?

Yes. Only an encryption layer is added; text, layout and images are preserved exactly.

Back to PDF

PDF password lock — restrict printing / copy / edit

Add a user / owner password and restrict printing, copying or editing on a PDF. AES 256-bit / 128-bit, all done by qpdf (WASM) inside your browser — neither the PDF nor the password leaves your device. Batch multiple files at once.

pdfsecurity

How to use

Drop a PDF and enter a user password, an owner password, or both. Pick an encryption strength (AES 256-bit / 128-bit) and which actions (printing, copying, editing, annotating) you want to allow, then click "Add password" — qpdf (WASM) produces a new encrypted PDF inside your browser. Compare side-by-side and download. Batch processing of multiple files is supported.

FAQ

Are the PDF and password uploaded?: No. qpdf runs as WebAssembly inside your browser, so neither the PDF nor the password leaves your device.
What's the difference between user and owner password?: The user password is required to open the PDF. The owner password is required to change the permissions (printing, copying, editing). Setting both is the most common pattern, but using one is fine too — if you only set one, the same value is used for the other internally.
Should I pick AES 256-bit or 128-bit?: Pick 256-bit unless you have a specific reason not to. It works with Acrobat 9 (2008) and every modern PDF viewer. Only fall back to 128-bit when you need to support Acrobat 7 / 8 era viewers.
Can I add a password to a PDF that's already encrypted?: Not directly. Unlock it first with the "PDF unlock" tool, then come back here to set a new password.
Does content stay intact?: Yes. Only an encryption layer is added; text, layout and images are preserved exactly.

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