Password Protect PDF
Lock a PDF with a password of your choice. The file is encrypted with AES-256, the same standard banks use, entirely in your browser: neither the document nor the password is ever uploaded.
This free tool password protects a PDF online with real encryption: AES-256, the same scheme banks use for e-statements. Once locked, the file demands the password before showing anything, in every PDF viewer, on every device. Type a password, click Protect PDF, and download the locked copy.
Everything runs locally in your browser, which is exactly what you want when locking a document sensitive enough to need a password: neither the file nor the password you choose is ever sent to a server, ours included.
How to password protect a PDF
- Select your PDF
Drag the file into the box above or click to browse. It stays on your device throughout.
- Choose a password
Type the password the recipient will need to open the file. Longer is stronger; a short numeric code protects against casual snooping but not against real attack.
- Click Protect PDF
The document is encrypted with AES-256 in about a second.
- Download and share
The locked copy downloads with a "-protected" suffix. Share the password over a different channel than the file, for example the file by email and the password by phone.
What locking a PDF actually protects
An open password is genuine encryption, not a polite request: the file contents are scrambled with a key derived from your password, and without it no honest or dishonest tool can read them. That makes it the right protection for documents crossing an untrusted channel: financial documents sent by email, payslips shared with a landlord, reports for a client.
Two honest limits. First, whoever knows the password can make an unlocked copy (with our own Unlock PDF tool, among others), so a password controls who can open the file, not what recipients do with it afterwards. Second, the strength is your password's strength: 1234 is guessed instantly, a long phrase is effectively unbreakable.
Forgot-password warning, before you lock
AES-256 cannot be cracked or reset. If the password for a locked PDF is lost, the document is gone for good, and no legitimate service can recover it. So before locking your only copy: keep an unlocked original somewhere safe, or store the password in a password manager. This warning is on the page because we also run the unlock tool, and "I locked it myself and forgot the password" is a request we genuinely cannot help with.
Why use this converter?
Private by design
Conversion runs in your browser. Your files are never uploaded, stored, or seen by anyone.
Genuinely free
No daily task limits, premium tiers, or watermarks. Local conversion costs nothing to run.
Instant results
No upload and download queues. Files convert in about a second, even on slow connections.
Works everywhere
Windows, Mac, Linux, iPhone, Android: any modern browser, no app or software install.
Frequently asked questions
How do I password protect a PDF for free?
Drop the PDF into the tool above, type the password it should require, and click Protect PDF. The locked copy downloads immediately. Free, no signup, and nothing is uploaded.
How strong is the protection?
The file is encrypted with AES-256, the strongest standard PDF encryption and the same scheme banks use for e-statements. The practical strength depends on your password: long passphrases are effectively unbreakable, short codes are not.
Is my file or password uploaded anywhere?
No. Encryption runs locally in your browser; the document and the password never leave your device. There is no server-side copy of either.
Can I remove the password later?
Yes, if you know it: our free Unlock PDF tool removes the password permanently and gives you an open copy. If the password is forgotten, the content is unrecoverable; that is what real encryption means.
Can I change the password on an already-protected PDF?
Unlock it first with the current password using our Unlock PDF tool, then protect the unlocked copy with the new password.
Will the locked PDF open on any device?
Yes. Password-protected PDFs are part of the PDF standard, so every mainstream viewer on Windows, Mac, iPhone, and Android will prompt for the password and open the file normally once it is entered.