About Protect PDF
Most PDF apps put password protection behind a paid plan, and many free web converters upload your contract or bank statement to a server before encrypting it. That is the wrong order: a document worth protecting should not be copied to an unknown machine just to acquire a password.
This tool encrypts the file inside your browser tab with AES-256, the cipher PDF 2.0 specifies. The user password opens the document with the permissions you choose; an optional owner password opens it without those limits. Printing, copying and editing are separate switches, and the protected copy downloads as the original filename plus -protected.pdf. Nothing is uploaded and no password is stored.
What this tool does
AES-256 encryption
The file is encrypted with AES-256, the strongest cipher the PDF standard specifies, directly in your browser.
User and owner passwords
One password opens the document with the permission limits applied; an optional owner password opens it with full access. Leave the owner field blank to reuse the user password.
Three permission switches
Allow or block printing, copying of text and images, and editing or form filling, each one independently.
Nothing leaves the device
The PDF and both passwords are used only inside the page. There is no upload, no server queue and no password logging.
Warnings before you save
The workspace states plainly that a lost password cannot be recovered and that reader permissions are advisory, not tamper-proof.
How to use Protect PDF
- 01
Add the PDF
Drop the file into the workspace. Files that are already password-protected are rejected with a prompt to unlock them first.
- 02
Type the user password
Enter the password readers will need to open the document, then type it again to confirm. It must be at least 4 characters.
- 03
Set an owner password if needed
Optional: add a second password that opens the PDF with full access. Leave it blank to use the user password for owner access.
- 04
Choose permissions
Decide whether readers may print, copy text and images, or edit page content and fill in forms.
- 05
Protect and download
Click Protect PDF, wait for the encryption to finish, then download the protected copy. Save the password — it cannot be recovered.
Supported formats and limits
- Input
- Output
- Processing
- Client-side, in your browser. Nothing is uploaded.
- Maximum size
- Up to 100 MB
- Requirements
- Chrome, Edge, Firefox or Safari
Limitations worth knowing
- A lost user or owner password cannot be recovered; this tool stores neither password.
- Permission switches are enforced by the reader and can be ignored by some viewers or scripts.
- PDFs that are already encrypted must be unlocked first — this tool does not replace or remove an existing password.
- Encrypting a digitally signed PDF invalidates its signature, and files are limited to 100 MB with browser memory as the practical ceiling.
Privacy and file handling
The PDF and both passwords are handled only inside your browser tab. The file is encrypted locally, nothing is uploaded, and the passwords are never logged or stored. The protected copy is written on your device, and closing the tab discards everything.
Read the full privacy policy