Protect a PDF with a Password
Encrypts your file with real, standard AES-256 encryption — not a cosmetic lock — using the genuine qpdf engine compiled to WebAssembly, the same engine used in professional desktop tools. The resulting file can't be opened by any PDF reader (including this site itself) without the correct password. The entire encryption happens in your browser; neither the file nor the password is ever uploaded to a server.
The file is encrypted entirely inside your browser — neither the file nor the password is ever uploaded to any server.
There is no way to recover the password if you forget it — losing it means the file can never be opened again. Keep it somewhere safe.
Drag a PDF file here or choose one
One file at a time
What this tool does
Adds a password to a PDF so it cannot be opened without it. This is real encryption applied to the file itself — not a viewer-level restriction — performed by qpdf, the well-known PDF tool, compiled to run inside your browser.
When to use it
- You are about to email or message a document containing personal or financial details.
- A contract or bank statement needs protecting before it goes into shared storage.
- You are archiving sensitive documents on a machine or external drive other people can reach.
How to use it
- Drag a PDF onto the drop area or choose it from your device.
- Type the password you want, then type it again in the confirmation field — you cannot continue while the two differ.
- Run the protection; an encrypted copy is created and downloaded, and your original file stays unprotected on your device.
A practical example
Input
A bank statement PDF and a password you choose.
Output
A PDF with the same contents that prompts for the password in any program that opens it — web browsers and phone readers included.
Limitations
- If you forget the password the file cannot be recovered. We do not keep it and it cannot be bypassed — save it somewhere safe before you close the page.
- An already-protected file cannot be protected again; you will see a message telling you to remove the existing protection first if you want to change it.
- Protection stops the file being opened without the password, but it does not stop someone who has the password from copying or printing the contents afterwards.
Privacy and processing
Encryption runs entirely inside your browser. Neither the file nor the password is sent to any server; we never see the password and never store it.
Technical notes
- The work is done by qpdf compiled to WebAssembly — a mature, audited implementation, chosen deliberately over hand-written encryption.
- The encryption is AES-256 using PDF's modern R6 scheme, which every current reader supports, so the file opens with the same password on any operating system.
- The same password is set as both the user (open) password and the owner (permissions) password — the simple, common case, rather than a separate password governing printing or copying.
Frequently Asked Questions
Real AES-256 encryption via the genuine qpdf engine (the same tool used in specialized desktop software) — not just a visual lock. The output file can't be read by an ordinary PDF program without the correct password.