PDF Protect

PDF Protect is a free, privacy-first web app for adding, updating, and removing password protection from PDF documents. All processing runs entirely in your browser: nothing is uploaded to any server.

Live at pdfprotect.me

Key Features

Core Functionality

• PDF Protection: Apply password-based protection to unprotected or already-opened PDF documents
• PDF Unlocking: Open password-protected PDFs in the browser when the correct password is provided
• Protection Removal: Remove password protection and download an unencrypted copy when owner-level access is available
• Metadata Removal: The enabled-by-default privacy switch clears the PDF Info dictionary and catalog XMP metadata when saving protected or unlocked copies
• Privacy-First: No server uploads, no accounts, and no background processing outside the browser

Security and Permission Controls

• User Password: Require a password to open the protected document
• Owner Password: Optionally require a separate owner password for changing permissions or removing protection
• Permissions-Only Protection: Leave the user password blank and use only an owner password to apply viewer-managed restrictions without an open-password prompt
• Shared-Password Fallback: If the owner password is left blank, PDF Protect reuses the user password so the file does not end up with an undisclosed random owner password
• Permission Toggles: Control printing, copying, modification, annotation, form filling, and document assembly
• Password Strength Feedback: Pattern-aware strength indicator plus confirmation checks for user and owner passwords. Common words with predictable additions, sequences, repeats, and dates lower the rating
• Common Password Warning: When setting a new password, the app checks it against a bundled list of 10,000 commonly-known passwords and shows an inline advisory if a match is found - no data leaves the browser
• Owner-Password Removal Safeguard: Prevents user-level sessions from removing protection when owner credentials are required

Password Recovery Scanning

• Dictionary Scan: When a password-protected PDF is loaded, click "Forgot password?" and choose a word list to run a common-password scan in the browser; no data is sent anywhere
• Bundled Word Lists: Two locally-stored password lists from the SecLists project are included: a 10,000-entry quick scan (default) and a 100,000-entry thorough scan
• Custom Word List: Load a local .txt (one candidate per line), .csv (each cell), or .md (one entry per line, excluding headings and fenced code). The scanner tries its unique candidates first, then the selected bundled list, skipping duplicates. Files stay in browser memory and are discarded when loading another PDF. The limit is 5 MB and 100,000 unique candidates
• List Toggle: Switch between the 10k and 100k bundled lists with a single click; the scan restarts immediately, with custom candidates first when loaded
• Auto-Fill: If the password is found it is automatically filled into the unlock field; just click Unlock to continue
• Cancellable: A cancel button stops the scan at any time, and manual entry is always available regardless of scan state
• Non-Blocking: Scans yield to the browser every 150 passwords so the UI stays fully responsive during long scans

Interface and Workflow

• Single-Page Workflow: Load, unlock, protect, and re-save documents from one browser-based interface
• Drag-and-Drop File Loading: Drop a PDF anywhere on the page, at any step, or browse manually
• Locked-State Detection: Detects whether a PDF is encrypted and switches into the unlock flow automatically
• Dark and Light Mode: Persisted theme preference across sessions
• Notifications: Dismissible toast messages that close on time, including on iOS Safari
• Accessibility: Visible keyboard focus, 44px touch targets, screen-reader status for long operations, and reduced-motion support

Browser Compatibility

• Optimal: Google Chrome and other current Chromium-based browsers
• Good: Firefox, Safari (including iOS and iPadOS), and Microsoft Edge (latest versions)
• Requirement: A modern browser with ES module, File API, and Web Crypto support

Development

Install the pinned development tools with npm ci, then run:

• npm run lint to lint first-party JavaScript and tests
• npm test to run the regression test suite

Versioning

The version lives in package.json. CI bumps the patch version on every push to main that changes app files, after tests and lint pass. Pushes containing only Markdown, docs/, or LICENCE.txt changes are ignored. Local assets and module URLs carry ?v=<version> to prevent stale CSS and JavaScript after deploys. Run npm run version:sync after editing to sync the footer and asset URLs; never hand-edit ?v=. CI commits these synced files with the version bump so Cloudflare Pages deploys them. For a manual minor or major bump, use the Tests workflow's Run workflow button on main and select the bump type.

Known Limitations

PDF Protect runs client-side, so performance depends on the browser, device, and PDF size. Files are capped at 50 MB. Very large or complex PDFs may take longer to load, unlock, or save. New protected output is currently limited to AES-256 by the bundled PDF engine. PDF permissions are best-effort viewer restrictions; some viewers may still allow actions such as text selection or copying. Certificate-based encryption is not supported.

Technical Notes

• Architecture: Static single-page app with vanilla JavaScript ES modules: no build step, no framework, no server
• PDF Engine: js/vendor/libpdf-core.js provides PDF loading, authentication, protection, and save operations
• State Handling: js/app.js manages the UI state machine and form validation; js/pdf-session.js isolates PDF authentication and protection logic
• Font Handling: UI fonts (Roboto, JetBrains Mono) are self-hosted in fonts/; Lucide icons are self-hosted in images/: no external font or icon requests
• Privacy: All PDF processing happens locally in your browser; your files and passwords are never uploaded. The only external request the site makes is to Cloudflare Web Analytics (cloudflareinsights.com), a cookieless, privacy-preserving page-view counter that collects no personal data and no file content
• Security: Content Security Policy restricts default-src to 'self'; the only permitted external origin is Cloudflare Web Analytics (script-src/connect-src). No third-party scripts, fonts, or trackers are loaded. The Cloudflare Pages _headers file also sends the CSP as a header with frame-ancestors 'none', plus X-Content-Type-Options, Referrer-Policy, and Permissions-Policy
• Tests: Focused Node-based regression tests covering file validation, theme selection, password confirmation, password strength, state transitions, permissions disclosure, and owner-password-based protection removal

Support

If pdfprotect is useful to you, please consider starring the repository to help others discover it.

Credits and Third-Party Licensing

• libpdf-core powers PDF encryption, authentication, and protection changes; bundled third-party licence notices are included directly in js/vendor/libpdf-core.js
• SecLists by Daniel Miessler: the passwords/10k-most-common.txt and passwords/100k-most-used.txt word lists are sourced from Passwords/Common-Credentials/10k-most-common.txt and 100k-most-used-passwords-NCSC.txt | MIT License
• Roboto Font by Christian Robertson | Apache License 2.0
• JetBrains Mono by JetBrains | SIL Open Font License 1.1
• Lucide 1.61.0 icons, self-hosted SVGs | ISC licence