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Frequently Asked Questions

Find answers to common questions about OSS Document Scanner and OSS CardWallet.

General​

Are these apps really free?​

Yes! Both OSS Document Scanner and OSS CardWallet are completely free and open source. There are no ads, no in-app purchases, and no premium features locked behind a paywall. They will nalways remain free and open source.

Is my data private?​

Absolutely. Both apps:

  • Process all data on your device
  • Never upload data to any server (unless you configure sync)
  • Don't include analytics or tracking
  • Are open source so you can verify yourself

What's the difference between the two apps?​

OSS Document ScannerOSS CardWallet
Scan paper documentsStore loyalty/membership cards
Auto edge detectionBarcode scanning
PDF export with OCRMultiple barcode formats
Document organizationCard organization

Both apps share common features like cloud sync, backup, and privacy-first design.

Where can I get support?​

How can I contribute?​

Scanning​

Why isn't edge detection working?​

Common causes and solutions:

  1. Poor lighting: Ensure even, adequate lighting
  2. Low contrast: Use a contrasting background (dark document on light surface or vice versa)
  3. Reflections: Avoid glossy surfaces that create glare
  4. Dirty lens: Clean your camera lens
  5. Complex background: Use a plain, solid-color background

Can I scan multi-page documents?​

Yes! Use batch scanning mode:

  1. Tap the camera button
  2. Tap the batch scan button left of the capture button
  3. Scan first page
  4. Continue scanning without saving
  5. All pages are combined into one document
  6. Tap Done when finished

Can I scan in low light?​

Yes, but quality may suffer. Tips for low light:

  • Enable flash
  • Use manual capture mode
  • Hold device very steady
  • Consider using additional lighting
  • Enable auto-enhancement after capture

Editing​

How do I rotate a page?​

  1. Open the document
  2. Select the page
  3. Tap the rotate button
  4. Choose rotation direction

Can I crop after scanning?​

Yes:

  1. Open the document
  2. Select the page
  3. Tap the crop/edit button
  4. Adjust the crop area
  5. Tap Apply

What filters are available?​

  • Original: No processing
  • Whitepaper: best for whitepaper type documents
  • Enhanced: Auto color/contrast improvement
  • Color: Improve colors and removed unwanted color shades. Best for cards

How does OCR work?​

OCR (Optical Character Recognition) extracts text from images:

  1. Open a scanned page
  2. Tap the OCR button
  3. Select language(s)
  4. Processing happens on-device
  5. Text can be copied or searched

Export​

What export formats are supported?​

  • PDF: Standard and with OCR text layer
  • JPEG: Compressed images
  • PNG: Lossless images

How do I reduce PDF file size?​

  1. Use lower quality setting
  2. Apply Black & White filter
  3. Use JPEG compression
  4. Reduce resolution (150 DPI for email)

Can I combine multiple documents into one PDF?​

Yes:

  1. Select multiple documents in list view
  2. Tap Export
  3. Choose "Single PDF"
  4. All documents are combined

How do I email a scan?​

  1. Open the document
  2. Tap Share
  3. Choose format (PDF recommended)
  4. Select your email app
  5. Document is attached to new email

Sync & Backup​

Which cloud services are supported?​

Direct sync via WebDAV:

  • Nextcloud
  • ownCloud
  • Synology NAS
  • Any WebDAV server

For other services, export and upload manually.

How do I set up sync?​

See our detailed Sync and Backup guide.

What happens if I edit on multiple devices?​

The most recent change typically wins. The app will:

  1. Detect the conflict
  2. Compare timestamps
  3. Keep the newer version

Are backups encrypted?​

Backups are ZIP files that are not encrypted by default. For sensitive documents:

  • Enable document encryption in app settings
  • Store backups in encrypted storage
  • Use encrypted cloud storage

Troubleshooting​

The app crashes on startup​

Try these steps:

  1. Restart your device
  2. Clear app cache (Settings > Apps > OSS Document Scanner > Clear Cache)
  3. Update to latest version
  4. Reinstall the app (backup first!)

Scans are blurry​

  • Hold device steady during capture
  • Ensure good lighting
  • Wait for auto-focus
  • Clean camera lens
  • Try manual capture with tap-to-focus

PDF export fails​

  • Check available storage space
  • Try lower quality setting
  • Reduce number of pages
  • Restart app and try again

Sync not working​

  1. Check internet connection
  2. Verify server credentials
  3. Test connection in settings
  4. Check server is accessible
  5. Review server logs for errors

OCR gives wrong text​

  • Use higher capture quality
  • Apply Black & White filter
  • Select correct language
  • Ensure text is clearly visible
  • Try different threshold settings

Technical​

What platforms are supported?​

  • Android: 7.0 (API 24) and above
  • iOS: 13.0 and above

How is the app built?​

OSS Document Scanner is built with:

  • NativeScript: Cross-platform framework
  • Svelte: UI components
  • OpenCV: Image processing
  • Tesseract: OCR engine
  • Zxing: Barcode engine

Where is source code located?​

Key directories in the GitHub repository:

DirectoryContents
app/Main application code
app/components/UI components
app/services/Business logic
opencv/OpenCV integration
plugin-nativeprocessor/Native processing plugin
cpp/Native C++ code

How can I build from source?​

See the Building Setup section in the main README.

Still Have Questions?​

If your question isn't answered here:

  1. Search existing GitHub issues
  2. Create a new issue with your question
  3. Check the source code for implementation details