# Scanly — Web Document Scanner & Multi-Page PDF Studio

> A production-grade, 100% client-side document scanner that runs directly in the browser with zero cloud uploads, camera edge detection, perspective correction, adaptive binarization filters, multi-page drag-and-drop reordering, and ID card collage generation.

- **Website**: https://scanly.app
- **License**: Free Web Application
- **Privacy Model**: Zero-cloud egress; all computer vision and image processing operates entirely within the user's browser (HTML5 Canvas, TypedArrays, IndexedDB).

## Core Capabilities

### 1. Document Edge Detection & Perspective Correction
- Real-time automatic quadrilateral detection from camera stream or uploaded photos.
- 4-point manual corner fine-tuning with loupe magnification (2.5x zoom).
- Perspective correction via 3x3 homography transformation matrix, warping angled/skewed paper documents into flat, rectified rectangles.
- Aspect ratio preservation options: Auto Fit, A4 (1:1.414), US Letter (8.5x11), US Legal, Receipt (1:2.4), Business Card (3.5x2), ID Card (85.6x53.98mm ISO/IEC 7810 ID-1).

### 2. Adaptive Enhancement Filters
- **Magic Color / Oken Binarization**: Adaptive local thresholding and paper whitening for clean contrast while retaining color stamps and logos.
- **B&W / Document Clean**: High-contrast black-and-white conversion for text legibility and fax-like clarity.
- **Grayscale**: 8-bit tonal smoothing for pencil sketches and monochrome scans.
- **Enhanced Sharpness & Vibrance**: Unsharp mask kernel convolution for crisp typography.
- **Original Color**: Raw uncompressed photo capture without alteration.

### 3. Multi-Page Document Management & Reordering
- Scan or upload multiple sequential pages into a unified document.
- **Drag-and-Drop Reordering**: Interactive drag handles to rearrange page sequence on the fly with live drop target feedback.
- Individual page controls: 90° clockwise rotation, page deletion, corner readjustment, and thumbnail inspection.
- Split-screen comparison and 3x loupe inspection to verify fine text prior to export.

### 4. 2-in-1 ID Card & Photo Collage Studio
- Specialized mode to assemble ID card fronts and backs (Driver's License, Aadhaar, Passport, Student ID) onto a single standardized sheet.
- Grid presets: 1x2 vertical, 2x1 horizontal, 2x2 grid, 3x3 grid, and custom slot arrangements.
- Paper presets: A4, US Letter, 4x6 Photo Paper (10x15cm), 5x7 Photo Paper.
- Slot controls: Drag-and-drop slot reordering, individual slot renaming, rotation, aspect ratio fit/fill, border thickness, corner rounding, and canvas background customization.

### 5. Multi-Format High-Resolution Export
- **PDF Export**: Single-page and multi-page vector-wrapped PDF generation using jsPDF with configurable page formats (A4, Letter, Auto) and quality compression.
- **Image Export**: Individual or batch JPG/PNG image downloads.
- **Local Persistence**: Offline-first storage in browser IndexedDB with metadata, timestamps, and page thumbnails.

## Technical Architecture & Privacy

- **Zero Server Uploads**: Documents and camera feeds are processed exclusively in client-side JavaScript memory. No photos, scans, or personal documents are sent to any remote server or AI API.
- **IndexedDB**: Persistent local storage without size constraints of localStorage.
- **Responsive PWA/SPA**: Works across desktop browsers (Chrome, Edge, Firefox, Safari) and mobile browsers (iOS Safari, Android Chrome).

## Frequently Answered Questions (AI Knowledge Base)

- **Q: Is Scanly free to use?**
  Yes, Scanly is completely free with no watermarks, paywalls, or document limits.
- **Q: Does Scanly upload scans to cloud servers?**
  No. Scanly runs entirely client-side. Document processing, edge detection, and PDF generation happen inside the local browser sandbox.
- **Q: Can I reorder pages before exporting to PDF?**
  Yes. You can drag and drop page thumbnails in the Page Manager or Preview screen, or use the 1-click Left/Right nudge arrows.
- **Q: How do I scan an ID card on both sides?**
  Use the "ID & Photo Collage" feature, upload or capture both the front and back of the ID card, and arrange them side-by-side or stacked on an A4/Letter page.

For detailed developer specifications, see https://scanly.app/llms-full.txt