ProofStamp is a privacy-first Progressive Web App (PWA) that lets you capture, hash, and securely store digital evidence — entirely offline and on your device.

Take a photo or upload a file, and ProofStamp automatically generates a SHA-256 fingerprint, records the timestamp and GPS location, and stores everything locally in your browser. Later, you can verify that a file hasn't been tampered with, or export a professional PDF certificate with a QR code.

• Capture & Upload — Take photos with your camera or upload any file (images, PDFs, documents)
• SHA-256 Hashing — Every file gets a unique cryptographic fingerprint via the Web Crypto API
• Combined Hash — A tamper-proof combined hash is generated from all file hashes + timestamp + GPS + random salt
• GPS Location — Optionally record the exact coordinates where the evidence was captured
• Verification — Re-upload a file to verify its hash matches the stored proof
• PDF Export — Generate a professional PDF with photo, metadata, all hashes, and a QR code
• Categories — Organize proofs: Apartment, Vehicle, Purchase, Communication, Contract, Workplace, Other
• Search & Filter — Find proofs by title, description, or category
• Gallery & List View — Switch between visual gallery and compact list layout
• Dark / Light / System Theme — Automatic or manual theme switching
• 5 Languages — German, English, Turkish, Spanish, French
• Offline-Ready — Full PWA with Service Worker, works without internet
• Privacy-First — Zero data leaves your device. No server, no cloud, no tracking
• Export / Import — JSON backup and restore of all your proofs
• IndexedDB Storage — Handles large files that wouldn't fit in localStorage

No build tools, no npm, no bundler — just open index.html.

Open index.html in your browser. Most features work, but GPS requires a secure context.

npx serve .

Then open http://localhost:3000. This enables GPS, Service Worker, and PWA install.

1. Onboarding — First launch shows a 3-step introduction
2. Create a proof — Tap the + button, add files/photos, title, category, and optionally GPS
3. View details — Tap any proof to see full metadata, file hashes, and combined hash
4. Export PDF — Generate a signed PDF certificate with QR code from any proof
5. Verify — Tap the ✓ button, select a stored proof, upload the same file — hashes are compared
6. Settings — Switch theme, language, export/import data, or delete all

Each proof contains:

{
  id, title, description, category,
  files: [{ name, type, dataUrl, hash }],
  timestamp,
  location: { lat, lng } | null,
  combinedHash,    // SHA-256 of: all file hashes + timestamp + location + salt
  salt,            // Random value for extra security
  createdAt
}

The combined hash ensures that even if someone knows the file and timestamp, they cannot predict the hash without the random salt.

ProofStamp/
├── index.html          # Single-page app
├── css/
│   └── style.css       # Dark/Light theme, responsive
├── js/
│   ├── app.js          # Core logic (IIFE pattern)
│   ├── i18n.js         # Translations (DE, EN, TR, ES, FR)
│   └── categories.js   # Categories & constants
├── img/
│   ├── favicon.svg
│   ├── icon-192.svg
│   └── icon-512.svg
├── manifest.json       # PWA manifest
├── sw.js               # Service Worker
└── LICENSE             # MIT

MIT