How to password protect a PDF
You are about to email a contract, a payslip or a scan of your passport. Email is a postcard: it passes through servers you do not control and sits in an inbox that may outlive the conversation. A password on the file is the one measure that travels with it.
Open the PDF, choose a password, and download the encrypted copy. Anyone opening it will be asked for that password. The encryption is applied in your browser with AES, so neither the file nor the password is ever sent to a server.
Protect a PDF nowStep by step
- Open the document
Select the PDF you want to protect. It is read in your browser and stays on your machine throughout.
- Choose a real password
Long beats complicated: four unrelated words are stronger and easier to pass on than eight scrambled characters. Avoid anything the recipient could guess from the document itself.
- Encrypt and download
You get a new, encrypted copy of the file. Your original stays unprotected on your disk, which is usually what you want.
- Send the password separately
Not in the same email. A text message or a phone call is enough, and it is the difference between protecting the file and merely labelling it.
Encryption versus a permissions flag
PDFs support two very different things. An open password encrypts the content: without it, there is nothing readable in the file. A permissions password only asks readers politely not to print or copy — and many readers simply ignore it.
If your goal is that the wrong person cannot read the document, you want the first one. The second is a hint to well-behaved software, not a lock, and it has never stopped anyone determined.
Choosing a password you can actually share
The password has to reach the recipient somehow, and that channel is the weak point. A password you have to spell out over the phone will get mistyped; a password sent in the same thread as the file protects nothing at all.
Four ordinary words are the good compromise: easy to read aloud, long enough to resist guessing, and hard to typo. Change it if you send the same document to several people over time.
What a password does not do
It protects the file, not the person you send it to. Once they open it, they can save an unprotected copy, screenshot it or forward it. Encryption controls who can read the document, never what they do next.
It also cannot be recovered. There is no reset link on a PDF: lose the password and the file is genuinely unreadable, including by you. Keep it somewhere before you send the document, not after.
Frequently asked questions
Is the encryption real, or just a setting?
It is real AES encryption of the file's contents. Without the password there is nothing to read, and no reader can display the document by ignoring a flag.
Does my password get sent anywhere?
No. The encryption happens in your browser on your own device, so both the file and the password stay on your machine.
What happens if I forget the password?
The file cannot be opened, by anyone, including us. Keep your unprotected original, or store the password somewhere safe before you send the encrypted copy.
Can I remove the password later?
Yes, if you know it. Unlock the document with the password and save the decrypted copy; without the password there is nothing that can be done.