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PDF Password Protector

Encrypt a PDF with a password.

Processed on your device. We never see your files.

How to use PDF Password Protector

What this tool does

The PDF Password Protector adds an open-password to a PDF document entirely within your browser. You pick a password, click Protect, and the tool uses the PDF encryption standard to produce a new file that requires that password every time it is opened. The output is a standard encrypted PDF that any modern PDF reader will recognise and prompt for the password.

Why you might need it

Sensitive documents — tax returns, legal contracts, medical records, employee payroll, non-disclosure agreements, business proposals, exam papers — should not sit as open files if they are going to be emailed or stored in a shared location. Adding a password before you share a file is one of the simplest ways to make sure only the intended recipient can read it. It does not replace proper access control, but it does create a meaningful barrier that stops casual snooping and protects the file if an email ends up in the wrong inbox.

Businesses sending client invoices, accountants sharing tax documents, or teachers distributing exam papers can benefit from this extra step. Scanned legal documents that contain signatures, bank details, or national identification numbers are particularly worth protecting before they travel anywhere outside the organisation.

How to use it

  1. Drop your PDF onto the dropzone, or click to browse for the file.
  2. Type a strong password into the password field. Click the eye icon to reveal what you are typing if you want to double-check it.
  3. Note the password down somewhere secure — a password manager or written record. There is no recovery option if you forget it.
  4. Click Protect PDF and wait for the tool to encrypt the file.
  5. Click Download protected PDF to save the encrypted copy.
  6. Test the result by opening the downloaded file in your PDF reader — you should be prompted for the password immediately.

Common pitfalls

The most common mistake is setting a weak or obvious password — a birth year, a pet’s name, or “password123” offers little real protection. Use a mix of letters, numbers, and symbols, or use a passphrase of four or more random words. Make it long enough that a brute-force attempt would take years.

Remember that the tool encrypts a copy of your PDF — it does not modify the original file in place. The file on your disk is still unprotected until you replace it with the downloaded version.

Some platforms (email providers, document management systems) strip or ignore PDF encryption when they process attachments. If you need your document to remain protected inside a system like Google Drive or Dropbox, check whether that system respects PDF passwords before relying on this alone.

Tips and alternatives

Choose a password that is memorable enough to give to the intended recipient without writing it in the same email as the file — send the file by email and the password by SMS, or vice versa. This two-channel approach is simple and significantly reduces the risk of both falling into the wrong hands.

If you need to protect many PDFs in a batch or apply more granular permissions such as preventing printing entirely, look for a desktop PDF editor with batch encryption support. For sharing confidential documents with a team, a dedicated document management platform with proper role-based access control is a stronger long-term approach than per-file passwords.

For removing a password you added previously, use the companion PDF Password Remover tool on this site. Both tools are client-side, so your documents never leave your device either way.

Frequently asked questions

Is my PDF uploaded to a server when I add a password?
No. The entire process runs inside your browser using JavaScript and the @cantoo/pdf-lib library. Your file is read into browser memory, encrypted locally, and the protected copy is produced on your device. Nothing is ever sent over the network. You can disconnect from the internet before using this tool and it will still work perfectly — check your browser's Network tab if you want proof.
What happens if I forget the password?
There is no way to recover a forgotten PDF password. The encryption standard used (AES-128 via the PDF security handler) means the password is required to decrypt the content — there is no back door or master key. Write the password down or store it in a password manager before you close the file.
What permissions does the tool set on the protected PDF?
The tool allows high-resolution printing and form filling but restricts modification, content copying, and document assembly. This covers most everyday use cases. The owner password is set to the same value you chose, which means opening the file with that password grants full access in PDF readers that support owner-level access.
Which PDF readers will ask for the password?
Any PDF reader that supports the standard PDF encryption specification will prompt for the password — this includes Adobe Acrobat, Apple Preview, Google Chrome's built-in viewer, Firefox, Microsoft Edge, Foxit, and virtually every other modern reader. The encryption is standard, not proprietary.
Can I protect a PDF that is already password-protected?
If the existing PDF requires a password to open, load it with the PDF Password Remover first to strip the old protection, then apply a new password here. If the PDF only has usage restrictions (editing or copying restrictions) but opens without a password, you can add a new open password directly with this tool.

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