Password-protect a PDF in your browser
Protect PDF files with a password free and 100% in your browser. Encrypt confidential PDFs locally with MuPDF, no upload, no sign-up, fully private.
100% private — files never leave your deviceKeep it safe — if you forget this password, the PDF can't be recovered.
How to use
- Select your PDF. Choose or drag in the PDF file you want to protect. It stays on your device the whole time.
- Set a password. Type the password that will be required to open the file. Pick something strong and memorable.
- Encrypt the PDF. Run the tool to encrypt your document locally in the browser with MuPDF.
- Download the protected file. Save the password-protected PDF. Anyone opening it will now be prompted for your password.
Features
- Real encryption, not a fake lock. Your PDF is genuinely encrypted with MuPDF so it cannot be opened without the password you set.
- Nothing leaves your device. All processing runs in your browser. Your confidential PDF is never uploaded to any server.
- Free with no sign-up. No account, no email, no watermark, and no limits hiding behind a paywall.
- Fast and offline-friendly. Encryption happens instantly on your own machine, so it works even on slow or private connections.
When to use it
- Lock a signed contract or NDA before emailing it to a client
- Protect medical records, lab results, or insurance forms shared with family
- Secure bank statements, tax returns, and payslips before storing them in the cloud
- Add a password to legal or HR documents containing personal data
- Protect a private report or proposal before sending it to a colleague
Is it private?
Your PDF is encrypted locally in your browser with MuPDF and is never uploaded to any server.
Frequently asked questions
Is this PDF protector free?
Yes, it is completely free with no sign-up, no email, and no watermark. There are no hidden limits or premium tiers.
Is my PDF uploaded anywhere?
No. Your PDF is encrypted entirely in your browser with MuPDF (WebAssembly) and never leaves your device, so it is safe for confidential documents.
What happens if I forget the password?
The password cannot be recovered. Because the file is truly encrypted, there is no backdoor or reset, so store your password somewhere safe before you close the page.
What file formats and limits apply?
This tool works with PDF files and outputs a password-protected PDF. Since everything runs locally, very large files are limited mainly by your device's memory.
Will the protected PDF open in other apps?
Yes. The result is a standard encrypted PDF, so Adobe Acrobat, Preview, browsers, and other readers will simply prompt for the password before opening it.
Does the password stop people from editing or printing too?
Setting an open password means the file cannot be opened at all without it, which also prevents viewing, editing, or printing until the correct password is entered.
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