Adding a password to a PDF is straightforward, but most people don’t know there are two different types of PDF passwords — and they protect very different things. Here’s what you need to know before you lock a document.
Two Types of PDF Passwords
Open password (user password) — prevents anyone from opening the file without the password. This is what most people mean when they say “password protect a PDF.” Without the password, the file can’t be opened at all.
Permissions password (owner password) — the file can still be opened without this password, but certain actions are restricted: printing, copying text, editing, or filling forms. This is useful for distributing read-only documents.
Most online tools (including ours) set the open password. If you need permissions-level restrictions, you’ll need a desktop tool like Adobe Acrobat.
How to Add a Password to a PDF
- Go to pdftoolshq.com/protect-pdf
- Upload your PDF
- Enter your password
- Download the protected file
The protected PDF uses 128-bit AES encryption, which is the standard for PDF security.
What PDF Password Protection Actually Does
A password-protected PDF is encrypted — the file contents are scrambled and can only be unscrambled with the correct password. This means:
- Someone who intercepts the file (in email, for example) cannot read it without the password
- The file is safe to store in cloud services — even if the storage is compromised, the encrypted file is unreadable
What It Doesn’t Protect Against
- Screenshots — once someone has the password and opens the document, they can screenshot the content. Password protection doesn’t prevent this.
- Password removal tools — weak passwords can be cracked. Use a strong password (12+ characters, mixed) for anything sensitive.
- The recipient sharing the password — if you send someone both the file and the password, they can share both.
For documents where you need stronger control, consider redacting sensitive sections before sharing, rather than relying solely on a password.
How to Remove a Password
If you own an encrypted PDF and want to remove the password (for example, to share it more easily), use the Unlock PDF tool. You’ll need to enter the current password to remove it — this is a security feature that prevents unauthorized unlocking.
Choosing a Good Password
- Use at least 12 characters
- Mix letters, numbers, and symbols
- Avoid dictionary words or anything personally identifiable
- Send the password via a different channel than the file (e.g. file by email, password by SMS)