Protect PDF
Encrypts the document with AES so it cannot be opened without the password. You can also set an owner password and permissions separately, which restricts printing, copying or editing while still letting anyone open the file.
Local processingAccepts PDFUp to 100 MB
Drop your file here
PDF · up to 100 MB each · you can also paste from the clipboard
Nothing is processed until you press the button below.
How this tool works
- 1qpdf, compiled to WebAssembly, runs inside this page.
- 2The document is encrypted in memory with the key length you choose.
- 3Your password is used and then discarded. It is never transmitted or stored.
What it will not do
- There is no password recovery. If you lose it, the document cannot be opened, by us or anyone else.
- Permission flags rely on the reader honouring them. They restrict well-behaved software; they are not a guarantee.
- Only AES is offered. The old 40-bit RC4 option is deliberately absent, because the underlying library refuses to write it and calling it an option would be a lie.
Where this runs
Protect PDF runs entirely inside this page. Your file is read by the browser, processed in memory and handed back to your downloads folder. It is never sent to a server, because there is no server involved in this tool.
Read the full processing model →Questions
No. The encryption runs in your browser, so the password and the document are both only ever in this tab's memory.