PDF Password Protect

About this tool

PDF Password Protect encrypts a PDF with AES-256 (PDF security handler revision 6) entirely in your browser, using a maintained fork of pdf-lib. Every page, image and stream is scrambled with a key derived from your password, so any modern reader, including Adobe Acrobat, macOS Preview, Chrome, Edge, Firefox and mobile viewers, asks for the password before showing anything. The password is never stored in the file or sent anywhere. You type it twice to catch typos, and it must be at least 4 characters. An optional owner password, which must differ from the open password, lets you allow or block printing, copying text and editing; those permissions are enforced by the reader, so treat them as a courtesy rather than a hard lock. Files that are already encrypted are refused: remove the old password with PDF Unlock first. There is no recovery if you forget the password, so keep an unencrypted original. Very old readers from before 2009 cannot open AES-256 files.

Why use it

• Real AES-256 Encryption: Page content is encrypted, not hidden behind a prompt, so every standard reader requires the password.

• Browser-Only Processing: The PDF and password never leave your device; nothing is uploaded.

• Confirm-Password Field: A second matching field catches typos before the file is locked.

• Permission Controls: An optional owner password lets you block printing, copying or editing in readers that honour PDF permissions.

• Free, No Watermark, No Signup: Output is unbranded with no daily limit, account, or paid tier.

How to use

1. Drop your PDF onto the upload area.
2. Type the password in 'User password (to open file)' — it must be at least 4 characters.
3. Re-type it in 'Confirm user password'; the tool stops with 'Passwords do not match' if they differ.
4. Optionally tick 'Set a separate owner password (advanced)', enter a different password and choose whether printing, copying text and editing are allowed.
5. Click 'Protect PDF' — the file is encrypted with AES-256 and a download button appears.
6. Open the downloaded file once to confirm the password works before you share it.

When it helps

• When emailing payslips, invoices, contracts or medical letters that only the recipient should read.
• When storing scanned IDs or tax documents in cloud folders shared with other people.
• When sharing a draft that colleagues may read and print but should not copy text from or edit.
• When a portal or policy requires password-protected PDF attachments.

Examples

Tips

• Send the password through a different channel from the file, for example by text message rather than in the same email.
• Use a long passphrase; encryption is only as strong as the password guessing it protects against.
• Keep an unencrypted original — a forgotten password cannot be recovered.
• Treat print, copy and edit permissions as a courtesy: they rely on the reader respecting them.
• Pair this with PDF Watermark to add a visible 'CONFIDENTIAL' mark on every page.

Frequently Asked Questions

Glossary

User Password

The password a recipient must type to open and view the PDF; it also derives the encryption key.

Owner Password

An optional second password that grants full access and controls permissions such as printing, copying and editing.

AES-256

The Advanced Encryption Standard with a 256-bit key, the cipher used by the strongest PDF security handler.

Security Handler Revision 6

The PDF 2.0 password scheme that pairs AES-256 with SHA-2 based key derivation.

Permission Flags

Bits in the encryption dictionary telling readers whether printing, copying, editing and form filling are allowed.

PDF Reader

Software that opens and renders PDF files — Adobe Acrobat, Preview, Foxit, browser viewers and mobile apps.