Protect PDF — Add AES-256 Password & Permissions

Password-protect a PDF online with AES-256 — free, private, no upload

If you need to send a tax return, a contract, a medical scan, a passport copy, a board minute, or any document with information that should not be casually visible, encrypting the PDF with a password is the right move. It takes ten seconds with GN PDF, costs nothing, and — unlike every "free" alternative — runs entirely in your browser. No file leaves your device. No password gets typed into a remote form. No "we just need your email first" friction.

How to add a password to a PDF

1. Drop your PDF onto this page, or click Choose PDF.
2. Type a strong open password — the password recipients will need to view the file. Confirm it in the second field.
3. Pick encryption strength. AES-256 is the modern standard and what we recommend. AES-128 is offered for compatibility with very old PDF readers.
4. Optionally set permissions: allow / disallow printing, text copying, editing and annotation. These are enforced by every compliant PDF reader.
5. Optionally set a separate owner password if you want to lock the permission settings independently.
6. Click Protect & Download. Save the encrypted file. Share it. Tell the recipient the password through a different channel (call, SMS, in person — never the same email as the file).

What you can protect

• Open password: required to view the document at all. The strongest form of protection.
• Print restriction: recipients can read on-screen but cannot send to a printer or "Save as PDF" to circumvent.
• Copy restriction: blocks text selection, copy, and clipboard operations.
• Modify restriction: stops editors from changing text, removing pages, or rearranging content.
• Annotation restriction: prevents the addition of comments, highlights, or signatures.

Practical password tips

The encryption algorithm is irrelevant if the password is "password123". A few rules:

• Length beats complexity — 16 random characters is stronger than 8 with !@#.
• Use a passphrase: four random words joined together is memorable and very strong.
• Never send the password in the same email as the file. Use SMS, a phone call, or a separate secure-share link.
• Use a different password per recipient if the file is sensitive enough.

What we do NOT do

We don't keep a copy. We don't escrow the password. We don't have a "forgot password" link — because there isn't one. If you lose the password, the file is gone for practical purposes. That is the design of strong encryption. Treat the password the same way you'd treat the key to a safe.

When to use Protect PDF instead of (or in addition to) other tools

• vs. Watermark: Watermarking deters casual misuse and identifies a copy. Encryption stops people from opening it at all. Sensitive files usually need both — watermark with the recipient name, then encrypt.
• vs. Redact: Redaction permanently removes the sensitive content from inside the file (use our Redact PDF tool). Encryption hides the whole file. Use redaction when only a few fields are sensitive; use encryption when the whole document is.
• vs. Server-side encryption services: Server-side tools are convenient but ask you to trust a stranger with your private file. GN PDF moves the entire encryption step to your browser, which is the only architecture that genuinely respects your privacy.

About this tool

Protect PDF uses the standard PDF 2.0 AES-256 encryption handler (revision 6) implemented in JavaScript and the browser's Web Crypto API. The PDF specification, the algorithm, and the password derivation function (PBKDF2-style) are well-documented public standards. The resulting file is fully compatible with Adobe Acrobat, Apple Preview, Foxit Reader, Sumatra, the built-in viewers in Chrome / Edge / Firefox, and every other compliant PDF software.