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PPDF123

Add a Password to a PDF

Add Password encrypts a PDF with a password you choose, using qpdf and a 256-bit key, so opening the file requires that password. We cannot reset a forgotten password.

Drag and drop files here, or click to choose

Accepts PDF · up to 500.0 MB per file · up to 20 files at once

You can also paste a file with Ctrl/Cmd+V, or from the clipboard menu.

Protect encrypts a PDF with qpdf `--encrypt` so opening it requires the password you set. Use it when a draft has to travel through email and you can send the password on a different channel.

The website exposes one `password` field. That value is both the user password and, unless the API sends `ownerPassword`, the owner password. Key length defaults to 256. The portal does not send `canPrint` or `canModify`, so both default off: print is `none`, modify is `none`. Recipients who only have the user password should not be able to print or edit in viewers that honor those flags. Test the file in a fresh viewer before you treat it as a compliance control.

Remember the password. We cannot reset it. Keep an unencrypted original if losing the secret would be catastrophic.

This is standard PDF password encryption, not remote DRM, not a certificate signature, and not a way to revoke a file already sent. A determined attacker with the bytes can still try offline guessing; use a long unique secret, not `1234` or your email password.

Some organizations forbid password PDFs because DLP cannot inspect them. Check that policy before encrypting company records. Do not restrict files you are not allowed to lock.

Unlock reverses this when you still know the password. On the web pages, other tools ask for the password and unlock the file for you; API callers run Unlock first.

If regulations forbid sending the plaintext PDF to a hosted encryptor, self-host.

Features

  • qpdf `--encrypt` with AES-256 by default
  • Portal password is user and owner; print and modify default to none
  • No password recovery
  • Anonymous API at /api/v1/security/add-password

When to use this tool

  • Ship a salary PDF with an out-of-band password
  • Protect a draft contract before email review
  • Add a password before uploading to a shared folder

How do I password protect a PDF?

  1. Upload the PDF you are allowed to restrict.
  2. Enter a strong password. Share it on a different channel than the file.
  3. Click Process and download the encrypted PDF.
  4. Open the download in a fresh viewer and confirm it prompts for the password.

Limits and edge cases

  • Lost passwords are unrecoverable here
  • Offline guessing is still possible; use a long unique secret
  • Not a substitute for access-controlled sharing
  • Upload limit on this website: 500 MB per file, sent in chunks above about 95 MB. A single direct API request body is capped at 100 MB.

Examples

  • Protecting a 3-page offer letter yields a PDF that prompts for a password on open
  • With website defaults, viewers that honor flags also block print and modify

Privacy for this tool

Files are uploaded over HTTPS, processed in memory or a short-lived temporary directory on our servers, and deleted when your result is ready. We do not keep copies for later browsing, training, or advertising profiles. See the Privacy Policy for retention details and AdSense cookie disclosures.

Frequently asked questions

Can you reset a lost password?
No. Keep an unprotected archive copy if loss would be catastrophic.
Can recipients still print?
Not with the website defaults. canPrint and canModify are off unless an API client sets them to true.
Is this enterprise DRM?
No. It is PDF password encryption. There is no remote revoke.
Does Protect remove signatures?
No. It encrypts the file. Test certified PDFs; encryption and signatures can interact badly.

Last updated:

Call this from code

Every tool on this site is a plain REST endpoint - no account or API key needed for anonymous use. Built for AI agents and developers as much as for browsers.

curl -X POST "https://pdf123.xyz/api/v1/security/add-password" \
  -F "[email protected]" \
  -F "password=your-password" \
  -o output.pdf

Also available as an MCP tool for agent clients that speak Model Context Protocol (JSON-RPC 2.0 over POST /mcp). Full API reference

Use it from an AI agent

Skill

Claude Code, Codex, Cursor and other AI agents can run Add Password for you with this skill: /skills/pdf123-protect.md

All agent skills

Files are used only for this processing job and deleted automatically afterward.