Take full control of your document security with PDF Lock & Unlock Passwords, a sleek, secure, and fully offline utility designed to lock, unlock, and manage your PDF files. Built on robust local cryptographic engines, your sensitive files never upload to the cloud—ensuring absolute privacy and state-of-the-art protection directly on your device.

Whether you need to shield a single financial statement, batch-protect hundreds of corporate contracts, or securely store your frequently used passwords, PDF Lock & Unlock Passwords offers an elegant, high-performance solution. All features—including unlimited bulk operations, large file support, and the secure password vault—are 100% free to use.

• AES-256 PDF Protection: Lock your documents using industry-standard AES-256 encryption compliant with PDF 2.0 specifications.
• Fast Security Assessment: Instantly check any document's current encryption state without parsing the full file, giving you immediate feedback.
• Local, Offline Processing: 100% of the cryptographic work is executed on your device. No cloud storage, no remote servers, and zero data exposure.
• Secure Local History Logs: Instantly track your history of protected or unlocked documents. Share files or open them directly from the app's clean, private audit log.
• Smart Folder & Path Mirroring: Keep your productivity organized. When exporting processed documents in bulk, the app retains your exact folder structures and automatically applies custom naming rules (e.g., appending "_locked" or "_unlocked").
• Modern Material You Design: Features an elegant, fluid Material 3 interface that dynamically adjusts to your device's theme, supporting seamless light, dark, and adaptive color transitions on both phones and tablets.
• Full TalkBack Accessibility: Out of the box support for Android screen readers, ensuring an inclusive experience for all users.

WHAT YOU GET 100% FREE

PDF Lock & Unlock Passwords is fully unlocked out of the box. Unlike other apps, we do not hide premium productivity tools behind expensive paywalls:

• Bulk Document Processing: Protect or unlock hundreds of documents simultaneously. Background processing works via Android WorkManager even if you close the app.
• Large PDF Support: Process files up to 250MB—perfect for scanning books, blueprints, and multi-page corporate reports.
• Frequent Passwords Vault: Save your common passwords securely on-device. Encrypted using the hardware-backed Android Keystore API and AES-GCM for fast, safe auto-applying during operations.
• Ad-Supported: All features are free, funded by unobtrusive banner ads and interstitial ads displayed between tasks.

GO AD-FREE (ONE-TIME UPGRADE)

Love the app but prefer a distraction-free environment?
• Simple One-Time Purchase: Permanently remove all banner and interstitial ads with a single $1.75 purchase.
• Direct Support: Helps fund ongoing development and offline updates!

PRIVACY & TRANSPARENCY
We believe in absolute transparency. PDF Lock & Unlock Passwords does not collect, transmit, or share your document contents, personal credentials, or file paths. All database histories, frequent passwords, and temporary files remain locally isolated inside your secure application container.