Protect PDF locks a PDF file with a password using AES encryption, which means the document's content is genuinely scrambled and can only be unlocked again by someone who knows the password — not just "locked" cosmetically.
Protect PDF — MEA Tools
Protect a PDF file with a password, choosing AES-128 or AES-256 encryption, right in your browser.
Open Protect PDF →Steps to add a password to a PDF
- Open tools.meaecosystem.com/protect-pdf.
- Upload the PDF file you want to protect.
- Type a new password, then retype it to confirm.
- Choose an encryption level: AES-128 or AES-256.
- Click protect PDF, then download the result.
AES-128 or AES-256 — which should you choose?
Both are equally secure for general use. AES-256 uses a longer key, making it theoretically stronger, but AES-128 is more compatible with older PDF reader software that might not support AES-256. If you're not sure what software the recipient will use, AES-256 is a safe default choice.
Don't lose your own password
Once a PDF is locked with a password, there's no way to open it again without the correct password — that's exactly what encryption is for. Make sure you store that password somewhere safe, like a password manager, so you don't lose access to your own document.
Frequently asked questions
Is my PDF and password sent to a server?
No. The entire encryption process runs directly in your browser — your file and password never leave your device.
What if I forget the password I set?
Unfortunately there's no way to recover access without the correct password — that's an inherent property of strong encryption. Store your password somewhere safe.
Can this be used to open a PDF that's already locked?
This tool is for adding a new password to a PDF that isn't locked yet. If your PDF already has a password and you want to remove it (with a password you know), use the Remove PDF Password tool instead.