100% Private, Fast, and In-Browser PDF Toolkit with Automated Pipelines.
Sealed locally in your browser. Zero cloud uploads. 100% offline-ready. No trackers.
⚡ Live Proof: 4.14 MB visa document compressed down to 1.8 MB entirely offline in-browser RAM (DevTools set to Offline, 0 network requests).
🌐 Launch Official Web App (pdf.sealkit.org) →
English | 简体中文
Why PDFSeal? In English, "Seal" has a charming double meaning:
- The Security Seal: Your documents are strictly sealed inside your local device's browser memory. Zero bytes are ever uploaded to any cloud server.
- The Seal Mascot 🦭: Meet Sammy the Seal, our friendly document guardian! Sammy ensures your private tax forms, legal contracts, and financial receipts remain strictly confidential and untracked.
"Drop your files in, let the little seal organize and process them, and leave with complete privacy peace of mind."
Visiting the root route (pdf.sealkit.org) opens a dedicated, high-density 14-tool matrix organized into 3 functional suites:
- 🔥 Popular Essentials: Merge, Compress, Sign & Stamp, Organize, Split, and PDF to Image.
- 🛡️ Privacy & Security Suite: Content Redaction, Metadata Scrubbing, Protect & Encrypt (AES-256), and Password Unlock.
- ⚡ Conversion & Automation: Image to PDF (with Scanner Enhancer), Watermark, Dynamic Page Numbering, and Batch Pipelines.
Quickly return to the 14-in-1 hub anytime by clicking the brand mascot logo 🦭 on desktop or mobile, keeping the main toolbar minimal and distraction-free.
All atomic utilities execute entirely client-side in browser RAM with zero arbitrary limits, no watermark penalties, and zero data leakage:
- Merge PDFs: Combine multiple documents in custom order with intuitive drag-and-drop. Features real-time page count aggregation, pre-merge thumbnail preview, and instant stage-three delivery relays to seamlessly chain into compression or protection.
- Organize & Rotate: Visual thumbnail grid workbench to reorder, multi-select with Shift or drag-box selection, rotate pages 90°/180°, and delete unneeded pages. Insert standard blank A4 pages anywhere (complete with multilingual watermark placeholders) or append external files, backed by a 30-step lossless undo/redo history stack and selective-page export.
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Split & Extract: Precision document slicing across 4 dedicated operational modes: Extract to Single PDF (isolate specific pages or ranges like
1-3, 5, 8-end), Burst to Single Pages (split the entire document into N distinct one-page files), Fixed Step Split (divide evenly every N pages), and Custom Range Segmentation. Export directly as standalone PDFs or bundled into a ZIP archive. - Smart Compress: Reduce file size by up to 90% across 4 fine-tuned modes: Balanced (300 DPI) for crisp readability; Extreme (150 DPI) for tight email caps; Lossless Object Stream Compression for structural optimization without rasterization; and Target Size Bisection (specify exact thresholds like ≤ 2MB, auto-tuning resolution and quality factors in-browser). All modes are guarded by a Universal Anti-Inflation Size Guard.
- Watermark & Protect: High-DPI transparent canvas watermark stamping engine. Supports multilingual typography, custom font sizing, opacity, tilt angles (-90° to 90°), repetitive grid tiling or centered placement, quick color swatches (Official Red, Navy Blue), and custom hex values, with direct chaining into owner-level permission encryption.
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Dynamic Page Numbering: Professional document pagination. Supports customizable format macros (
{n},{total},Page {n} of {total}, etc.), 6 header/footer alignment anchors, odd/even mirror flipping, and cover page skipping (starting page 1 on sheet 2). Features proprietary Whiteout Masking (full-ribbon or local bounding box) with canvas color auto-sampling to cleanly conceal misaligned legacy page numbers. - Sign & Stamp: Engineered for rigorous contract signing. Supports freehand drawing, typography-generated signatures, and uploaded seal images. Proprietary local background flattening automatically strips camera shadows and paper whiteout, with instant ink recoloring (Original, Ink Black, Deep Blue, Stamp Red). Features Smart Auto-Trim Bounding Boxes to crop away transparent whitespace for pixel-perfect placement, and automatic aspect-ratio preservation for official circular and square seals. One-click batch initial placement across all, even, odd, or non-terminal pages, backed by a persistent local seal library and positioning presets.
- PDF to Image: High-fidelity rasterization of PDF pages into crisp PNG or JPG images. Choose between Standard 150 DPI for web distribution and Print-Grade 300 DPI for archival clarity. Download individual pages directly from thumbnail cards or export the complete set as a zipped archive in one click.
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Image to PDF (with Scanner Enhancement): Convert batches of PNG, JPG, WebP, and BMP images into a unified multi-page PDF. Includes a proprietary In-Browser Document Scanner Enhancement Engine (CamScanner-Style):
$O(W \times H)$ illuminance normalization flattens phone/wrist shadows and whitens yellowish paper backgrounds, with 3 optimized filter modes (Auto Color preserving red seals, Crisp B&W high-contrast binary text, and Clean Grayscale), live real-time thumbnail updates, and interactive Hold to Compare original view. Offers standardized A4 dimensions (with auto-orientation and proportional centered margins) or adaptive native-image sizing. - Protect & Encrypt: Modern high-grade AES-256 client-side encryption. Protect documents with an Open Password (User Password) to prevent unauthorized reading, and set an Owner Password to enforce granular operational restrictions (prohibiting unauthorized printing, text/image extraction, form alterations, and annotating), securing distributed contracts without sending keys to the cloud.
- Unlock & Strip Restrictions: Permanently remove encryption locks and permission restrictions. After validating the document password, the client engine restructures the internal object streams to permanently purge encryption dictionaries, yielding a clean, unrestricted, plaintext PDF.
- Scrub Metadata: Essential privacy purification for government, corporate audits, and sensitive disclosures. Deeply audits and permanently purges hidden forensic metadata and underlying attributes: document titles, author names, company names, software fingerprints (Word, WPS, InDesign), timestamps, camera GPS coordinates, private application dictionaries (PieceInfo), and embedded thumbnail caches.
- Redact Content: High-assurance physical byte-level redaction for sensitive text and images in document content streams. Draw visual boxes with automatic snap-to-text boundary precision, or batch-mark via smart search (keywords or localized regex presets for ID/SSN, phone, bank cards, emails, and universal dates). Supports per-mark and whole-page replication, blackout, whiteout, dark gray, custom color blocks, and [REDACTED] stamps. Re-parses output to verify zero extractable text residue before export; target text is permanently destroyed and cannot be recovered.
- Local Privacy Vault: Secure in-browser document staging and archive powered by IndexedDB with zero network telemetry. Leverages native Web Crypto SHA-256 content hashing for automatic deduplication, toggleable grid/list views, automatic or one-click post-processing storage, and instant reloading into downstream editing tools.
💡 Unified Delivery & Context-Aware Next-Action Workflow Engine: All core interactive processing tools feature a standardized three-step workflow (« ① Upload File → ② Configure & Process → ③ Delivery & Next Relays »). Features before/after size & ratio metrics, full-screen preview, one-click re-download, « Return to Edit » state preservation, and an intelligent Next-Action Workflow Engine that infers the most relevant downstream operation (e.g., auto-recommending compression for files > 10MB, sequential re-pagination after merging, and tamper-proof AES encryption after contract signing) with zero-copy in-memory relay and clean silence on ZIP archives.
🛡️ Smart Workspace Draft Preservation & Multi-Tool Navigation: Powered by bounded
<KeepAlive>caching with delivery-aware lifecycle management. Seamlessly jump across tools to cross-reference or configure documents without losing your draft, files, or settings. Completed tasks automatically reset upon return for instant next-job readiness.
Chain multiple standalone PDF operations into an automated, single-click assembly line:
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Battle-Tested Presets:
- 📁 Tender & Sensitive Document Sanitizer: Metadata scrubbing
$\rightarrow$ Balanced compression$\rightarrow$ Anti-leak watermark stamping. - 🛡️ Privacy & Content Redaction: Metadata scrubbing
$\rightarrow$ Keyword/regex PII redaction$\rightarrow$ AES permission encryption. - 🧾 Expense Receipts Auto-Packer: Multi-image to A4 PDF conversion (with automatic shadow removal & paper whitening)
$\rightarrow$ Audit page numbering$\rightarrow$ Smart compression$\rightarrow$ EXPENSE REPORT watermark. - 📑 Contract Batch Stamping & Archive: Permission unlock
$\rightarrow$ Last page signature stamping$\rightarrow$ Security watermark.
- 📁 Tender & Sensitive Document Sanitizer: Metadata scrubbing
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Visual Drag & Drop Pipeline Builder:
- Reorder, configure, add, or remove steps with live node compatibility port validation.
- Real-time multi-file batch execution with step-by-step progress tracking, cancellation support, and active event loop yielding.
- Batch export options: sequential download, automatic local Vault archiving, and dynamic token naming (
{original}_{date}_{index}).
- No-Admin Desktop & Mobile Installation: Install PDFSeal as a standalone, windowed application directly from Chrome, Edge, or Safari without requiring IT administrator privileges. On mobile, add it to your home screen for full-screen offline execution.
- 100% Airplane Mode Reliability: Powered by
vite-plugin-pwaand Workbox, 400+ core dependencies (including CJK font maps, WASM binaries, and standard font binaries) are automatically pre-cached. - F5 Refresh Proof: Press
F5while completely disconnected from the internet, and PDFSeal reloads and operates at 100% capacity without a single network request. - Secure Context Requirement: Modern browsers (iOS Safari, Android Chrome) strictly enforce PWA Service Worker caching on Secure Contexts (
https://orhttp://localhost). For local area network (LAN) mobile testing, use HTTPS or an SSL reverse proxy to enable full offline installation.
- Thumb-Friendly Dual-Mode Layout: Clean separation between desktop and mobile. Mobile devices feature a minimal header, a thumb-reachable bottom navigation bar for top workflows (Merge, Image-to-PDF, Compress, Sign), and an intuitive sliding bottom sheet for all 14 core utilities. Desktop view remains 100% untouched.
- Thumb-Zone Sticky Action Bars: Heavy multi-file tools (Image-to-PDF, Smart Compress) feature a persistent bottom execution bar, keeping primary triggers (e.g., "Export PDF", "Compress") always within single-handed thumb reach without scrolling past dozens of uploaded items.
- Compact 3-Column Responsive Grid: Dense, thumb-friendly thumbnail layout with sliding parameter sheets for rapid mobile collation.
- Responsive Modals & Vault Picker: Re-architected dialogs and Vault document pickers with horizontal category scroll tabs and full-width touch buttons, eliminating text squishing on narrow viewports.
- Web Share API Integration: Share processed PDFs directly via native OS sheets (AirDrop to Mac, save to Apple Files / Google Drive, or send via WhatsApp/WeChat) with automatic direct-download fallback.
- Touch-Optimized Signing: Draw signatures effortlessly with finger or stylus with zero scroll interference (
touch-none) and enlarged touch resize handles. - Mobile Camera & Memory Guard: Instant multi-photo document collation with automatic resolution scaling protection (prevents mobile Safari canvas OOM crashes on 48MP+ camera photos).
- Add to Home Screen Guidance: In-drawer guidance for Android one-click installation and step-by-step iOS Safari guidance to launch as a standalone, zero-address-bar native app.
- Transfer sensitive documents between devices with client-side AES-GCM-256 encryption.
- Encryption keys are kept solely in the URL fragment (
#key=...) and are never sent to servers or CDNs.
- Zero Server Uploads: Processing is executed 100% inside your browser using WebAssembly and JavaScript (
pdf-lib+pdf.js). - Offline Capable: Disconnect your Wi-Fi or enable Airplane Mode, and all core features will still work flawlessly.
- Zero Tracking: No user tracking, no third-party telemetry, no user fingerprinting.
- Framework: Vue 3 (Composition API,
<script setup>) - Build Tool: Vite 6 with VitePWA
- Styling & UI: Tailwind CSS & Lucide Icons
- PDF Engine: pdf-lib & pdfjs-dist
- Security & Cryptography: Native Web Crypto API (SubtleCrypto AES-GCM-256, SHA-256)
- Internationalization: Custom lightweight reactive i18n architecture with zero runtime bloat (Full native support for English, Deutsch, Español, Français, 日本語, 简体中文 with URL parameter query syncing and global hreflang search indexing). Clean language-based design using standard native endonyms.
- Local Storage: IndexedDB with structured transactional stores (Privacy Vault)
- Performance & Scheduling: Active Event Loop Yielding to prevent UI freezing during intensive WASM/canvas computations
- Testing Suite: Vitest & Puppeteer (36 unit test suites, 230 unit tests 100% passing, plus headless browser E2E regression suites)
# 1. Clone the repository
git clone https://github.com/sealkit-org/pdfseal.git
cd pdfseal
# 2. Install dependencies
npm install
# 3. Start local development server
npm run dev
# 4. Run automated unit test suite
npm test
# 5. Run headless browser end-to-end (E2E) regression tests
npm run test:e2e
# 6. Build for production (generates PWA Service Worker)
npm run build# One-click start with Docker Compose (serves on http://localhost:8080)
docker compose up -dPDFSeal is independent and community-driven. If this tool saved you time or frustration:
👉 Support Sammy the Seal on Ko-fi ☕ 🐟
PDFSeal is free software licensed under the GNU Affero General Public License v3.0 (AGPLv3). If you run a modified version of PDFSeal or provide it as a network service, you must release your complete modified source code under the same AGPLv3 terms.
If your organization requires using PDFSeal in a commercial proprietary environment, intranet on-premise deployment, or custom integration without the copyleft obligations of the AGPLv3, please obtain an Enterprise Commercial License.
For commercial inquiries, licensing agreements, or enterprise deployments, contact us at:
📫 license@sealkit.org or via our portal at pdf.sealkit.org.