Protect PDF
Add a password to a PDF, without uploading it.
Drop a PDF to password-protect
Encrypted with AES-256, right here in your browser · drag & drop, paste, or click to browse
Runs entirely in your browser — nothing you enter is uploaded or sent to a server.
The password is real AES-256 encryption, but it's only as strong as the password you pick — and because everything happens on your device, nobody including us can recover it if you forget it. The permission checkboxes are weaker still: they're flags a reader chooses to honour, not enforcement. Read our full disclaimer.
About this tool
Emailing a payslip, a signed contract or anything with your address on it is the moment you want a password on the file. This adds one, using AES-256 — the strongest encryption the PDF format supports — and does it entirely in your browser. That last part matters more than usual here: every other site offering this needs you to upload the confidential document to their server first, which is a strange thing to do with a file you're trying to keep private. Nothing leaves your device, including the password.
A sensible password
Three or four unrelated words — something like "harbour-lantern-fig-quiet" — beats "P@ssw0rd!" comfortably. It's far longer, so much harder to attack, and you can actually pass it to a colleague over the phone.
How to use
- 1Drop in the PDF you want to lock.
- 2Choose a password and type it twice — longer beats more punctuation.
- 3Optionally block printing, copying, editing or commenting once it's open.
- 4Protect and download. The new file asks for the password every time it's opened.
Features
- AES-256 encryption, the strongest the PDF specification defines.
- Optional restrictions on printing, copying, editing and commenting.
- The file and the password stay on your device — no upload, no server, no account.
- Works on any PDF the browser can read, whatever produced it.
Frequently asked questions
How strong is this really?
The encryption is AES-256, the same standard used for full-disk encryption, and it's the strongest the PDF format defines — there's no back door in it. The practical strength is your password: a short or common one can be attacked offline no matter how good the cipher is.
What if I forget the password?
The document is gone. That's not us being unhelpful — the encryption happened on your device with no copy of the key anywhere, so there's genuinely nothing to recover from. Save the password somewhere before you send the file.
Do the printing and copying restrictions actually stop anyone?
Not really, and it would be dishonest to imply otherwise. They're flags recorded in the PDF, and Acrobat and other mainstream readers respect them, but nothing in the format enforces them — plenty of software ignores them entirely. Use them as a signal of intent; rely on the password for actual confidentiality.
Why only 256-bit? Other tools offer 128-bit and 40-bit.
Because those older modes use RC4, which is broken, and the library we use flatly refuses to write them without an override that says "yes, make this insecure". We'd rather not offer a weaker option to someone who came here to protect a document.
Is my document uploaded to be encrypted?
No — and this is the tool where that matters most. The encryption runs in your browser through WebAssembly. The PDF and the password both stay on your device, which is exactly the property you want when the file is worth protecting.
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