📌 PinBridge

Get OTPs from your Android phone on your computer — instantly, securely, and automatically.

PinBridge mirrors one-time passwords (OTPs) received via SMS on your Android device to your Chrome browser in real-time. No more switching between devices to copy verification codes.

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💡 Why PinBridge?

Many users rely on a secondary phone for SIM-based OTPs, which creates real friction — especially when the device isn't nearby during urgent authentication.

Carrying a second phone just for OTPs is frustrating. I used to forget mine all the time — and only realize it when I urgently needed an OTP.

So I built PinBridge.

Now, OTPs from my secondary phone show up instantly on my laptop via a browser extension and web app.

No switching devices. No interruptions. No stress. Just seamless authentication.

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✨ Features

• 🔄 Real-Time OTP Sync — OTPs appear on your browser within seconds of being received on your phone
• 🔐 End-to-End Encryption — All OTPs are encrypted with AES-GCM before leaving your phone
• 🌐 Chrome Extension — View OTPs directly in your browser with auto-fill support
• 📱 Web Dashboard — Access your latest OTP from any browser at pin-bridge.vercel.app
• ☁️ Cloud Sync — Sign in with Google to sync pairing across devices without re-scanning QR codes
• 🟢 Live Device Status — See whether your phone is online or offline in real-time
• 🔔 Desktop Notifications — Get notified instantly when a new OTP is received
• ✍️ Auto-Fill — OTPs are automatically pasted into input fields on websites
• 📡 Background Sync — The Android app runs silently in the background, even after reboots
• 🛡️ CAPTCHA Protection — Accidental unpairing is prevented with a 4-digit verification code

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🏗️ Architecture

┌──────────────┐     SMS      ┌──────────────────┐
│  SMS Sender  │ ──────────► │   Android App    │
│  (Bank etc.) │              │  (PinBridge)     │
└──────────────┘              └────────┬─────────┘
                                       │
                              AES-GCM encrypted
                                       │
                                       ▼
                              ┌──────────────────┐
                              │   Firebase Cloud  │
                              │   (Firestore)     │
                              └────────┬─────────┘
                                       │
                          ┌────────────┼────────────┐
                          │            │            │
                          ▼            ▼            ▼
                   ┌────────────┐ ┌─────────┐ ┌──────────┐
                   │  Chrome    │ │  Web    │ │ Presence │
                   │  Extension │ │ Dash.   │ │  Server  │
                   └────────────┘ └─────────┘ └──────────┘

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📦 Project Structure

Directory	Description
android/	Android app — Kotlin, Jetpack Compose, Hilt, Firebase, Socket.IO
extension/	Chrome Extension — Manifest V3, Webpack, Firebase SDK, Socket.IO
web/	Web Dashboard — Vite, Vanilla JS, Firebase SDK
server/	Presence Server — Node.js, Express, Socket.IO, Redis, Firebase Admin
functions/	Firebase Cloud Functions (reserved)
logo/	App logos and branding assets

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🚀 How It Works

Step 1 — Sign In

Open the PinBridge Android app and sign in with your Google account. On the Chrome extension, sign in with the same Google account.

Step 2 — Pair Devices

From the Chrome extension, click Start Pairing to generate a QR code. Scan it with the Android app, or enter the pairing code manually. The devices are now linked with a shared encryption key.

Step 3 — Receive OTPs

When an SMS with an OTP lands on your Android phone, PinBridge:

1. Detects the SMS and extracts the OTP
2. Encrypts it with AES-256-GCM using the shared secret
3. Uploads the encrypted payload to Firebase Firestore
4. The Chrome extension decrypts and displays it instantly

Step 4 — Use OTPs

• The extension shows a notification and copies the OTP
• Websites with OTP input fields get auto-filled
• You can also click Fetch Latest to manually pull the most recent OTP

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🔒 Security

Layer	Technology
Encryption	AES-256-GCM (end-to-end, key never sent to server)
Authentication	Firebase Auth with Google Sign-In
Storage	Firebase Firestore with security rules
Transport	HTTPS / WSS (TLS)
Local Storage	Android EncryptedSharedPreferences

The encryption key is generated during pairing and shared only between your phone and browser via QR code. Firebase servers never see your OTPs in plaintext.

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🛠️ Setup & Development

Prerequisites

• Android Studio (Arctic Fox or later)
• Node.js 18+
• Chrome browser
• Firebase project with Firestore, Auth, and Functions enabled

Android App

cd android
./gradlew assembleDebug
# Install on device
adb install -r app/build/outputs/apk/debug/app-debug.apk

Chrome Extension

cd extension
npm install
npx webpack --mode production
# Load in Chrome:
# 1. Go to chrome://extensions
# 2. Enable "Developer mode"
# 3. Click "Load unpacked" → select the extension/ folder

Web Dashboard

cd web
npm install
npx vite build
# Deploy to Vercel or serve locally:
npx vite

Presence Server

cd server
npm install
# Configure .env with Firebase Admin credentials and Redis URL
node index.js

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📱 Supported Platforms

Platform	Minimum Version
Android	8.0 (API 26)
Chrome	116+ (Manifest V3, Side Panel API)
Web	Any modern browser

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🗂️ Tech Stack

Component	Technologies
Android	Kotlin, Jetpack Compose, Hilt, CameraX, ML Kit, WorkManager
Extension	JavaScript, Webpack, Firebase JS SDK, Socket.IO Client
Web Dashboard	Vanilla JS, Vite, Firebase JS SDK
Backend	Node.js, Express, Socket.IO, Redis, Firebase Admin SDK
Error Tracking	Sentry (Android + Extension)
Database	Firebase Firestore
Auth	Firebase Authentication (Google Sign-In)
Hosting	Vercel (Web), Render (Presence Server)

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📄 License

MIT License — see LICENSE for details.

© 2026 Muhammed Naseel