Protect PDF with Password — Free, In-Browser

Real Encryption vs. Permission Flags — What Your Password Actually Does

Encrypting a PDF with a password and restricting a PDF are different things with very different security strength. This tool applies the first: it encrypts the entire file with a user password, making the bytes unreadable without that password. The second — "no printing," "no copying" — are only flags in the file that a polite PDF reader chooses to honour. Many readers ignore them entirely, so calling them "protection" is misleading.

Your protection here is real: the user password you set uses AES-128 encryption, which means the file stays locked until someone enters the correct password. A forgotten password makes the document permanently unrecoverable. The security rests entirely on password strength, not algorithm tricks.

How It Works: No Upload, No Trace

The entire process runs in your browser. Your PDF and password never leave your machine — nothing travels to our servers, no logs exist, and no one can intercept your file or key. When you add a password, the tool encrypts the file in memory and gives you a protected copy to download. The original stays untouched on your device.

If you need to open the protected PDF later and have lost the password, there is no recovery option, no backend reset, and no way to retrieve it — by design, that's the only way to guarantee security.

Password Rules and Strength

The minimum password length is 4 characters, though shorter passwords are trivially weak. A strength meter updates as you type, running from "Very weak" up to "Very strong" based on length and on how many character classes you have used. A strong password uses all four character types and at least 12 characters.

Choose a password you can remember, or store it safely if you write it down. If you use a password manager, let it generate one — 16+ random characters is ideal. Do not rely on a weak password; it defeats the AES-128 encryption entirely.

Unlock a Protected PDF Later

If you already have a protected PDF and know the password, use the companion tool to unlock PDF and remove the password protection. Provide the correct password, and you get an unencrypted copy.

What Stays Behind: Owner vs. User Password

Internally, the tool sets both a user password (what you enter) and an owner password (defaults to the user password). The user password is required to open the file; the owner password controls edits and metadata changes. Since no permission restrictions are set, both passwords do the same thing: lock and unlock. Changing the owner password separately is not exposed in this tool, because the goal is a simple, single-password lock.