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PDF · up to 50 MB · processed in your browser, never uploaded
Protect PDF — free online tool
Lock a PDF with a password so only people you give it to can open it. The document is encrypted with 256-bit AES — the same standard used by banks and government agencies — right in your browser, so neither the file nor the password is ever sent to a server. Use it for payslips, tax documents, medical records, contracts and anything else that should not be readable if the email is forwarded or the drive is lost. It runs entirely in your browser — your file never leaves your device, there is nothing to install, and it is free with no sign-up.
- AES-256 encryption applied in-browser using the qpdf engine compiled to WebAssembly
- Anyone opening the file — in Acrobat, Preview, Chrome, a phone — is asked for the password
- Content, images and text remain fully intact once unlocked; nothing is flattened
- The password never leaves your device
- Free, instant and works on files up to 50 MB
How to protect pdf
- 1Upload the PDF to protect.
- 2Enter a strong password — at least 12 characters mixing words, numbers and symbols.
- 3Click Protect PDF; encryption takes a second or two.
- 4Download the protected file and test-open it to confirm the prompt appears.
- 5Share the password through a different channel from the file — a message or call, not the same email.
Frequently asked questions
What if I forget the password?
There is no recovery. AES-256 encryption cannot be bypassed, by us or anyone else, which is the point of using it. Store the password in a password manager and keep an unencrypted copy of the document somewhere safe, such as an encrypted drive.
Can I set separate permissions, like allowing viewing but not printing?
This tool sets a single open password: the document is either fully accessible with the password or not at all. Owner-password permission flags (no print, no copy) are widely ignored by viewers and offer little real protection, so we do not present them as security.
Is a protected PDF safe to email?
The content is encrypted, so intercepting the file yields nothing without the password. Send the password separately — never in the same message — and prefer a long passphrase, because short passwords can be guessed by brute force even against strong encryption.
Will the recipient need special software?
No. Every mainstream PDF viewer — Adobe Acrobat and Reader, macOS Preview, Chrome, Edge, Firefox, iOS and Android viewers — supports AES-256 encrypted PDFs and will simply prompt for the password.
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