Add a password to your PDF with AES-256 encryption — nothing is uploaded, it all happens in your browser.
This PDF is already password-protected. Use Unlock PDF first if you want to change its password.
Passwords don't match.
AES-256 is the modern PDF 2.0 standard. Use RC4-128 only if the file must open in very old PDF readers.
PermissionsYour file and password are never uploaded — encryption runs entirely in your browser using the Web Crypto API.
Protect PDF adds real password encryption to your document — the same kind of protection built into Adobe Acrobat's "Protect with password" feature. Anyone opening the file in any standard PDF reader (Acrobat, Preview, browser viewers, mobile apps) will be asked for the password before they can view it.
Upload your PDF, enter and confirm a password, and optionally adjust the encryption strength or permissions under Advanced options. Tap Protect PDF, then download your password-protected file.
Choose a strong, unique password — PDF password protection deters casual access effectively, but like any password-based encryption, it isn't designed to withstand an unlimited, determined offline attack against a weak password. For sensitive documents, use a long password with a mix of letters, numbers, and symbols.
What is AES-256 encryption and why does it matter?
AES-256 is the same encryption standard used by governments and banks to protect classified and financial data — it's considered effectively unbreakable by brute force with current technology, given a strong password. It matters here because it's the actual protection your PDF gets, not just a password prompt cosmetically added on top of an unprotected file.
Is my password sent anywhere?
No. Everything — reading your PDF, encrypting it, and generating the protected file — happens locally in your browser. Your password is used only in memory for that calculation and is never transmitted, logged, or stored.
What's the difference between the user and owner password?
The user password is required just to open and view the file. The owner password (if set separately) controls permissions like printing or editing — some PDF readers respect these restrictions even without a user password.
Will this work with any PDF reader?
Yes — password protection is a standard part of the PDF format, supported by Adobe Acrobat, Preview, browser PDF viewers, and mobile apps. AES-256 requires PDF 2.0-aware readers (all modern software); RC4-128 is available if you need compatibility with very old readers.
Can I remove the password later?
Yes — use the Unlock PDF tool with the password you set here.