This Encrypt PDF tool password-protects any PDF entirely in your browser. Upload a file, choose an open password (and an optional owner password), pick AES-256 for modern readers or RC4 for legacy compatibility, and optionally restrict copying or editing. The encrypted PDF downloads immediately — nothing is uploaded to a server. It is built for developers, legal teams, and anyone who needs to share a sensitive document with a password gate before opening. AES-256 follows the PDF 2.0 standard and opens correctly in Adobe Acrobat, Chrome, Preview, and other major readers.
Features
Password-protect PDFs with AES-256 (recommended) or RC4 (legacy)
Separate open password and optional owner password
Optional restrictions on copying and modifying content
Detects already-encrypted files and prompts you to decrypt first
Outputs a standard password-protected PDF that opens in major readers
Runs entirely in your browser — your file and passwords never leave your device
How to use the Encrypt PDF
Drop or select the PDF you want to protect.
Enter an open password and confirm it — this is required to view the file.
Optionally set a different owner password and choose AES-256 or RC4.
Toggle copy or edit restrictions if you need tighter permissions.
Click Encrypt & download and save the protected PDF.
Example
Input
contract.pdf · Open password: secret · Algorithm: AES-256
Output
contract-encrypted.pdf — opens only after entering the password
AES-256 encryption with an open password.
Common errors & troubleshooting
The PDF will not load in the tool. — The file may already be encrypted. Use Decrypt PDF to remove the existing password, then encrypt again.
Encrypt & download stays disabled. — Enter an open password and make sure the confirmation field matches exactly.
Recipients cannot open the encrypted PDF. — Share the open password securely. If they use a very old reader, try RC4 instead of AES-256.
You forgot the password after encrypting. — Passwords cannot be recovered from an encrypted PDF. Keep the password in a safe place and retain an unencrypted copy.
Frequently asked questions
What does Encrypt PDF do?
It adds password protection to a PDF so the file cannot be opened without the password you set. Encryption runs locally in your browser.
What is the difference between AES-256 and RC4?
AES-256 is the modern PDF 2.0 standard and is recommended for new documents. RC4 is an older algorithm for compatibility with legacy PDF readers.
What is an owner password?
The open password is required to view the PDF. The owner password controls permissions such as printing and copying; if you leave it blank, the open password is used.
Can I restrict copying or editing?
Yes. Use the Restrict copying and Restrict editing toggles before encrypting. Recipients can still open the file with the password, but permissions follow what you chose.
Is my PDF or password uploaded?
No. Encryption happens entirely in your browser. Your file and passwords are never sent to a server.
Can I encrypt a PDF that is already password-protected?
Remove the existing password with Decrypt PDF first, then encrypt the unlocked file with your new password.
Related tools
Decrypt PDF — Remove password protection from an encrypted PDF.
Watermark PDF — Add a diagonal text watermark to every page.
Merge PDFs — Combine multiple PDFs into one, with reordering.
Split PDF — Extract pages or ranges (e.g. 1-3,5,7-9) into a new PDF.
Rotate PDF — Rotate all pages or a selection by 90/180/270°.
Compress PDF — Shrink a PDF by re-rendering each page to a JPEG at a chosen quality and resolution.
PDF to Text — Extract selectable text from a PDF as plain text or Markdown.