Protect a PDF with a password
Lock a document so it cannot be opened without a password. The file is encrypted with AES-128 — strong, and supported by every PDF reader in common use, including the one built into your phone.
Free, no account, and your file is never uploaded.
How to password protect a PDF
- 1Choose the PDF you want to lock.
- 2Set the password that will be needed to open it.
- 3Protect, then download the encrypted file.
Worth knowing
- The password is never transmitted. Encryption happens in your browser. The password is not sent anywhere, not stored, and not recoverable by anyone here — including us.
- There is no way to recover it. That is the point of encryption, and it is worth saying plainly: if you forget the password, the document cannot be opened. Save it somewhere before you close the tab.
- AES-128, deliberately. AES-256 exists but older readers refuse it. AES-128 is strong enough for any ordinary document and opens everywhere, which matters when you are sending the file to someone whose software you cannot control.
- Encryption controls opening, not behaviour. A password stops someone opening the document. It does not reliably stop printing or copying once it is open — those permission flags are advisory and many readers ignore them.
When to use it
- Emailing a payslip, contract or statement that contains personal details.
- Sharing financial documents with an accountant.
- Keeping a copy of ID documents in a shared folder.
Questions
- What encryption is used?
- AES-128, which every common PDF reader can open, including the ones built into phones.
- What happens if I forget the password?
- The document cannot be opened. Nobody can recover the password, so store it somewhere safe before closing the page.
- Can a password stop people printing or copying?
- Not reliably. A password controls opening the file; print and copy restrictions are advisory and many readers ignore them.
Read the guide
- PDF open password vs permissions password: what each does
An open password stops a PDF from opening without the password. A permissions password controls actions such as printing or editing in readers that honor those limits. They solve different problems.
- Electronic vs digital signature: what a signed PDF actually proves
Most PDFs only need an electronic signature — a sign that you agreed. A digital signature is a different thing: a certificate that proves who signed and that the file has not been altered since.
Related PDF tools
They are all in the PDF workspace, and the rest of the free tools — invoices, QR codes, scanned-PDF enhancement and file compression — need no account either.