Step 1 — Create your free Firebase project

1. Go to: console.firebase.google.com
2. Click Add Project → give it any name → Create
3. Click the Web icon (</>) → Register app
4. Copy the firebaseConfig values shown
5. Open this software's HTML file in Notepad → find FIREBASE_CONFIG near the bottom of the code
6. Replace the placeholder values (YOUR_API_KEY, etc.) with your copied config, save the file
7. In Firebase Console → build → Firestore Database → Create Database → start in test mode

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /schools/{schoolId} {
      allow read, write: if schoolId == "YOUR-SECRET-SYNC-CODE";
    }
  }
}

Step 2 — Put the file online (so every device can open it)

Upload the same HTML file to a free host like Netlify or your own web hosting, so every device opens the exact same URL instead of separate local copies.

Step 3 — Connect your devices

Go to Settings → Cloud Sync, generate a Sync Code on your first device, then enter that exact same code on every other device (computer, phone, tablet). They will all update instantly, live.