Signvoy

Free Tool

Add AES-256 password encryption to your PDF — restrict who can open it. Powered by mupdf in your browser. No upload, no account, no watermark.

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How it works

Protect your PDF in three steps

  1. 1

    Upload your PDF

    Drag and drop your PDF onto the tool or click to browse. The file loads in your browser — never sent to any server.

  2. 2

    Set a password

    Enter your chosen password and confirm it. Use at least 4 characters — longer passwords are stronger. The same password will be required to open the protected PDF.

  3. 3

    Download the protected PDF

    Click 'Download protected PDF'. mupdf applies AES-256 encryption in your browser and the protected file downloads immediately.

Why use Signvoy

Strong encryption, no upload

AES-256 encryption

The tool uses mupdf's AES-256 encryption — the same standard used by governments and financial institutions — applied entirely in your browser.

Instant download

Encryption is applied by the mupdf WebAssembly module and your browser downloads the protected file immediately — no queue, no waiting.

Your file stays on your device

Everything runs locally. Your PDF and your password are never sent to any server — close the tab and both are gone.

Need to send a document for others to sign?

This free tool covers self-serve, one-step document work. Signvoy's full platform adds everything a business needs: send to multiple signers, enforce a signing order, get a tamper-evident audit trail, automate reminders, and attach a certificate of completion to every finished document.

  • Multi-party signing
  • Tamper-evident audit trail
  • Certificate of completion
  • Reusable signing templates
  • Sequential & parallel routing
  • Automatic reminders
  • REST API & webhooks
  • Conditional field logic
Get started free →See all features

FAQ

Common questions

What happens if I forget the password?
There is no recovery option — the encrypted PDF cannot be opened without the correct password. Store your password securely before downloading.
What encryption standard is used?
AES-256 (Advanced Encryption Standard with a 256-bit key), applied via mupdf compiled to WebAssembly. This is a widely accepted strong encryption standard.
Will the protected PDF work in Adobe Acrobat?
Yes — the password-protected PDF is a standard encrypted PDF that opens in Adobe Acrobat, Apple Preview, and most other PDF viewers when the correct password is entered.
Can I remove the password later?
Yes — use the free Unlock PDF tool. You will need to provide the current password to remove the protection.

Want to learn more? Read the full guide: How to Password Protect a PDF Online for Free →

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