Encrypt PDF
Password-protect a PDF with AES-256 or RC4 encryption.
Your PDF and passwords are encrypted locally in your browser and nothing is uploaded to a server.
Need to remove a password instead? Try Decrypt PDF.
About Encrypt PDF
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.
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