V1 Release Candidate

Messaging Without
Infrastructure

BridgeLink is a decentralized mesh messaging app that uses WiFi Aware to send end-to-end encrypted messages — no internet, no cell towers, no servers. Just people connecting directly.

0 Servers Required
E2E Encrypted
5m Pairing Range
500 Max Hops
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Scroll to explore

What is BridgeLink?

A new paradigm for private communication

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No Servers, No Tracking

BridgeLink doesn't use the internet at all. Messages travel directly between devices using WiFi Aware technology, forming a peer-to-peer mesh network. There are no servers to hack, no metadata to harvest, no accounts to create.

🌎

Mesh Networking

When your recipient isn't nearby, other BridgeLink users automatically relay your encrypted messages through the mesh. Each device becomes a node in the network, extending range far beyond a single WiFi Aware connection.

🤝

Physical Proximity Pairing

You can only add contacts by being physically near them (within 5 meters). This isn't a limitation — it's a feature. It guarantees you know exactly who you're talking to. No friend-of-friend requests, no strangers.

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Who Is It For?

Anyone who values genuine privacy: activists, journalists, festival-goers, remote communities, emergency responders, or anyone in situations where traditional infrastructure is unavailable or untrustworthy.

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How It Works

WiFi Aware mesh networking explained

1

Discover

BridgeLink uses WiFi Aware (Neighbor Awareness Networking) to discover nearby devices. Each device runs both PUBLISH and SUBSCRIBE sessions simultaneously, creating a robust discovery mesh.

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2

Pair

When adding a contact, you appear as a random 3-word name (e.g., "apple-bridge-cloud") to prevent billboard attacks. After connecting, both users verify a 4-digit PIN to confirm identity. Only then are real usernames revealed.

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3

Send

Messages are end-to-end encrypted and broadcast to nearby peers. If your recipient is nearby, they get it directly. Otherwise, relay nodes carry it through the mesh until it reaches them — even days later.

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4

Confirm

BridgeLink is "honest about uncertainty." Messages stay as "Queued" until the recipient actually confirms receipt with a cryptographic ACK. No false "Delivered" statuses — you always know the real state.

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The Mesh in Action

Messages hop from device to device until they reach their destination

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Core Features

Everything you need for truly private communication

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Direct & Mesh Delivery

Messages are delivered directly when your contact is nearby, or relayed through the mesh network. You always see the actual delivery method: Direct, Mesh, or Queued.

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Group Chats

Create encrypted group conversations. Groups use their own key pair, and unknown senders appear anonymized until you add them as contacts — encouraging real-world connections.

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Relay Hub Mode

Turn your device into a mesh supernode. Hub mode forwards to 30 peers (vs 10 normal), stores 30MB of relay data, and can run automatically overnight while charging.

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Postman Mode

Physically carry messages for your contacts. Doubles storage capacity to 200 messages and prioritizes delivery to your contacts' recipients. Be a human relay node.

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App Lock

Protect the app with PIN, TOTP authenticator codes, or biometric unlock. Auto-lock on screen off, intruder photo capture, and screenshot blocking keep your data safe.

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Backup & Restore

Export encrypted backups protected with Argon2id + AES-256-GCM. Restore on a new device with your password and 32-character backup code. ICE contacts are automatically notified.

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Battery Optimized

Intelligent power management with AlarmManager-based scheduling. Wake locks reduced by 75%, running at approximately 1.2x normal battery drain with full mesh functionality.

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Security Architecture

Multiple layers of protection by design

Layer 1

End-to-End Encryption

All messages are encrypted using ECDH (Elliptic Curve Diffie-Hellman) key exchange. Messages can only be decrypted by the intended recipient. Relay nodes transport ciphertext they cannot read.

  • ECDH key exchange for shared secret derivation
  • Cryptographic message signing prevents tampering
  • Relays are blind couriers — they can't read content
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Layer 2

Hardware-Backed Key Storage

Your identity private keys are encrypted at rest using AES-256-GCM via the Android Keystore. The master key never leaves the secure hardware (TEE/StrongBox), protecting against root extraction and forensic analysis.

  • AES-256-GCM encryption at rest
  • Keys stored in TEE/StrongBox secure hardware
  • Protection against root extraction
  • Automatic migration from legacy storage
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Layer 3

Anti-Billboard Protection

During pairing, users appear as random 3-word names generated from a 2048-word list (8.5 billion combinations). This prevents bad actors from broadcasting phone numbers or URLs as usernames.

  • Random discoverable names (e.g., "apple-bridge-cloud")
  • Real usernames hidden until PIN verification
  • Suspicious pattern detection for phone numbers, URLs, and emails
  • Color-coded warnings (green = safe, red = suspicious)
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Layer 4

Peer Reputation System

An automatic graduated penalty system that detects and handles bad actors without user intervention. Points accumulate for protocol violations, with penalties escalating from warnings to permanent bans.

10 pts Warning
20 pts Throttle (1 msg/min)
50 pts Temp Ban (1 hour)
100 pts Permanent Ban
  • Automatic decay: 1 point per 10 minutes (recovery from transient issues)
  • Contact protection: 2x higher thresholds, 2x faster decay
  • Silent penalties: No feedback to attackers
  • 21 violation types covering all protocol aspects
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Group Chats

Encrypted group conversations with a unique privacy model

Room Approach Architecture

Each group has its own EC key pair shared among members. Messages are encrypted using ECDH between the sender's private key and the group's public key, ensuring only group members can read content.

Privacy-First Design

Messages from unknown senders appear as truncated IDs (e.g., "D4F2A9...F9G7B2") with an "Add to view messages" prompt. This creates a natural incentive to meet people in person before seeing their messages.

Active Participation Rewarded

Group messages are delivered to active members within seconds. Members who don't come online within 1 hour of message delivery may miss messages — a deliberate "shadow-ban" that discourages lurking and encourages engagement.

Member Management

Two-tier system: Ignore (local, hide messages from specific members) and Remove (network-wide, creator only, propagated to all members for 7 days).

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Privacy Features

Comprehensive protection for your data and identity

🔒 App Lock

Multiple authentication methods to protect your conversations:

Authentication Methods

  • PIN Lock — 4-8 digit PIN, SHA-256 hashed
  • TOTP — 6-digit authenticator app codes
  • Biometric — Optional fingerprint authentication

Lock Triggers

  • Lock on screen off (default: ON)
  • Lock when leaving the app
  • Auto-lock after inactivity: Immediate / 1m / 5m / 15m / 30m / Never

Intruder Detection

  • Silent front camera photo on failed unlock attempts
  • Max 50 photos with auto-cleanup
  • Gallery viewer with delete options
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📨 Send Mode Privacy

Choose how your messages are transmitted based on your privacy needs:

DIRECT_ONLY
Maximum metadata privacy. Messages are only sent directly to the recipient — never relayed through the mesh. Prevents any third party from seeing even the encrypted message.
MESH_ONLY
Maximum location privacy. Messages are only sent through mesh relays — never directly. Prevents the recipient from knowing you were physically nearby.
BOTH Default
Balanced approach. Uses both direct and mesh delivery for maximum reliability. Best for most users.
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🚫 Screenshot Blocking

FLAG_SECURE prevents screenshots and screen recording of the app, keeping conversations private even from screen capture tools.

🔔 Hidden Notifications

Option to hide sender names in notifications, so passers-by can't see who's messaging you from your lock screen.

🔄 Encrypted Backups

Backups use Argon2id key derivation + AES-256-GCM encryption. Both a password and 32-character backup code are required for restoration.

🆘 SOS Alert

Emergency SOS button notifies your ICE (In Case of Emergency) contacts. ICE contacts are also automatically notified when you restore from a backup.

Relay & Mesh Modes

Extend the network and carry messages further

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Relay Hub Mode

Transform your device into a mesh network supernode that actively helps messages reach their destinations.

Peer Forwarding
Normal: 10 peers Hub: 30 peers
Relay Storage
Normal: 10 MB Hub: 30 MB
Rate Limit
100 msg/min
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Overnight Relay Mode

Set your device to automatically become a relay hub during configured hours when plugged in to charge. Perfect for supporting the mesh while you sleep.

  • Auto-enables when charging during configured hours
  • Display modes: Stats / Digital Clock / Analog Clock
  • Independent light/dark theme
  • Auto-disables when you interact with the device
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Postman Mode

Be a human relay node. Carry messages for your contacts by physically traveling between locations. Ideal for bridging gaps in the mesh where people are far apart.

  • Keeps messages until direct delivery to recipient
  • Doubles message capacity to 200 messages
  • Priority: Recipient > Contact > 10-peer threshold
  • Perfect for commuters, travelers, or community connectors
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Network Health Monitoring

BridgeLink continuously monitors network health with signal bars that measure peer count and connection staleness. Session health checks run every 90-300 seconds, with automatic teardown and rebuild if WiFi Aware enters a zombie state.

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Settings Guide

Complete walkthrough of every setting and option

Main Settings

The main settings page provides quick access to your profile, network performance monitoring, and app information.

Username

Your display name visible to contacts. Set during initial setup. This is the name others see in their contact list and chat screens.

Network Performance

Real-time display of your mesh network statistics including connected peers, messages relayed, and delivery success rates. The signal bar indicator provides at-a-glance network health.

About

App version information and acknowledgments.

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UI Settings

Customize the look and feel of BridgeLink.

Theme

Switch between light and dark themes. The app respects Material Design 3 guidelines with appropriate contrast ratios in both modes.

Text Size

Adjust message text size for comfortable reading. Useful for accessibility or personal preference.

Educational Tips

Toggle helpful tips and explanations throughout the app. Useful when learning BridgeLink's features; can be disabled once familiar.

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Privacy Settings

The most comprehensive settings page with full control over your app's security posture.

App Lock

Enable/disable the app lock. When enabled, requires authentication to access the app.

Biometric Authentication

Use fingerprint as an alternative to PIN/TOTP for faster unlocking. Requires a primary authentication method to be set first.

Settings Lock

Require authentication before accessing settings. Prevents unauthorized configuration changes.

Two-Factor Authentication (TOTP)

Add a second factor using any TOTP authenticator app (Google Authenticator, Authy, etc.). Generates 6-digit codes that rotate every 30 seconds.

Lock Triggers

Configure when the app automatically locks: on screen off, when leaving the app, or after a period of inactivity (Immediate / 1m / 5m / 15m / 30m / Never).

Notification Privacy

Hide sender names in notifications so passers-by can't see who's messaging you from the lock screen.

Screen Security

Enable FLAG_SECURE to block screenshots and screen recording of the app.

Intruder Detection

Silently captures a front-camera photo on failed unlock attempts. View captured photos in a built-in gallery. Stores up to 50 photos with automatic cleanup.

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Background Operation Settings

Control how BridgeLink operates in the background and participates in the mesh network.

Send Mode

Choose between DIRECT_ONLY (max metadata privacy), MESH_ONLY (max location privacy), or BOTH (balanced, default). Each mode affects how your messages are transmitted through the network.

Postman Mode

Enable to physically carry messages for your contacts. Doubles capacity to 200 messages and prioritizes delivery to your contacts' recipients.

Relay Hub Mode

Turn your device into a mesh supernode. Increases peer forwarding from 10 to 30 and relay storage from 10MB to 30MB. Rate limited at 100 messages per minute.

Overnight Relay Hub

Configure automatic relay hub activation during specified hours when charging. Choose display mode (Stats / Digital Clock / Analog Clock) and theme.

Background Reliability

Fine-tune how aggressively BridgeLink maintains background connections. Balances between reliability and battery consumption.

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Backup & Restore

Securely backup and restore your BridgeLink data.

Create Backup

Export an encrypted backup file containing your identity, contacts, and message history. Protected with Argon2id key derivation and AES-256-GCM encryption. You'll need both your password and a generated 32-character hex backup code to restore.

Restore from Backup

Import a previous backup file to restore your identity and data on a new device. Requires both the original password and 32-character backup code. ICE (In Case of Emergency) contacts are automatically notified when you restore.

SOS Alert

Emergency button that sends an alert to all your designated ICE contacts. Designed for situations where you need immediate help from trusted contacts.

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Advanced Settings

Diagnostic and development tools for power users.

Debug Log

View the unified debug log showing all system events, message routing, peer connections, and protocol activity. Useful for troubleshooting connectivity issues.

Queue Stats

Monitor the outbox queue with detailed statistics on pending, sent, and failed messages. Shows batch timing and delivery type breakdowns.

Peer Reputation

View the reputation metrics dashboard showing all tracked peers, their violation points, and current penalty status. Includes an interface to unban peers who were incorrectly flagged.

Onboarding

Re-run the initial setup walkthrough. Useful if you want to review the app's introduction or show it to someone else.

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Technical Specifications

Protocol constants and system constraints

Message Limits

Max Message Size 500 characters
Max Batch Size 1,200 bytes
WiFi Aware Chunk Size 140 bytes
Text Only No media attachments

Network

Max TTL 7 days / 500 hops
Pairing Range ≤ 5 meters
WiFi Aware Range ≤ 15 meters
Peer Timeout 6 minutes

Rate Limits

Per Contact 500 msg/day per pair
Relay Quota (Normal) 20 per sender
Relay Quota (Hub) 30 per sender
Unknown Senders 25/day per sender, 1000/day global

Storage

Relay Storage (Normal) 10 MB
Relay Storage (Hub) 30 MB
Postman Capacity 200 messages
Intruder Photos 50 max

Timing

Active Conversation Batch 3 seconds
Quick Reply Batch 10 seconds
Background Batch 30 seconds
Health Check Interval 90-300 seconds

Platform

Platform Android
Min SDK API 26 (Android 8.0)
Target SDK API 34 (Android 14)
Requirement WiFi Aware capable device

Message Delivery Flow

Queued
Message saved and waiting for broadcast
Broadcasting
PING validates peers, then sends to responding nodes
Mesh Sent
Relayed through network, awaiting recipient ACK
Delivered
Recipient confirmed receipt (Direct or Mesh)

Download BridgeLink

Available for Android devices with WiFi Aware support

Recommended

Google Play Store

The recommended way to install BridgeLink. Get automatic updates and verified builds from the official store.

Get it on Google Play Requires Android 8.0+ with WiFi Aware

Direct APK Download

Download the APK directly for sideloading. Ideal when the Play Store is unavailable or you prefer manual installs.

Download APK V1 Release Candidate — See FAQ for sideloading info
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System Requirements

Android 8.0 (API 26) or higher
WiFi Aware capable device
WiFi enabled (no internet needed)
At least one other BridgeLink user nearby

BridgeLink is a free, community-driven project. If you find it useful, consider supporting development:

Frequently Asked Questions

No. BridgeLink uses WiFi Aware (Neighbor Awareness Networking), a peer-to-peer technology built into modern Android devices. It works entirely without internet, cell towers, Bluetooth, or any external infrastructure. Your phone's WiFi hardware communicates directly with nearby devices.

A single WiFi Aware connection reaches up to about 15 meters. However, through the mesh network, messages can hop up to 500 times and survive for 7 days, meaning they can travel as far as the chain of BridgeLink users extends. In a dense area like a campus or festival, messages can traverse significant distances.

No. All messages are end-to-end encrypted before they ever leave your device. Relay nodes transport ciphertext that they cannot decrypt. Only the intended recipient, who has the corresponding private key, can read the message content.

Physical proximity pairing (within 5 meters) is a deliberate security design. It ensures you always know exactly who you're adding — you can see them and verify their identity. This eliminates impersonation, catfishing, and social engineering attacks that plague server-based messaging apps. There are no friend requests from strangers.

BridgeLink is "honest about uncertainty." A message stays "Queued" until the recipient actually confirms receipt with a cryptographic acknowledgment (ACK). This means your recipient either hasn't been near a BridgeLink user who's carrying your message, or the mesh path hasn't connected yet. Messages persist for up to 7 days, so there's time for the mesh to deliver.

Currently, BridgeLink is Android-only. It requires WiFi Aware (Neighbor Awareness Networking), which is an Android technology. Apple has not implemented WiFi Aware in iOS, so iPhone support is not possible at this time.

Direct means the recipient was nearby and received your message directly from your device, confirmed by their ACK. Mesh means the message was relayed through one or more intermediate devices before reaching the recipient. Both are end-to-end encrypted and secure — the difference is just the path taken.

WiFi Aware has strict bandwidth constraints — messages are chunked into 140-byte pieces. The 500-character text limit and 1,200-byte batch size are designed to work reliably within these constraints. Sending media would require orders of magnitude more bandwidth and would be impractical over the mesh. Text-only keeps the network fast and efficient for everyone.

BridgeLink has been extensively optimized for battery life. Wake locks have been reduced by 75%, and the app uses AlarmManager-based scheduling with timed lock acquisition. Expect approximately 1.2x normal battery drain — a significant improvement from early versions that caused 2-3x drain.

BridgeLink is designed for situations where traditional infrastructure may be unavailable or untrustworthy — and that includes app stores. By offering a direct APK download for sideloading, we ensure you can always get BridgeLink even if you don't have access to the Google Play Store, if the Play Store is blocked in your region, or if you simply prefer not to use Google services. This is especially important for the privacy-conscious users and activists that BridgeLink is built for. To install the APK, you'll need to enable "Install from unknown sources" in your Android settings. The APK is the same build as the Play Store version — just a different distribution channel.

Yes, as long as you download it directly from this official website. The APK is the identical build to the Google Play Store version. We recommend only downloading BridgeLink from this website or the official Play Store listing — never from third-party APK sites. If in doubt, compare the cryptographic signature of the APK with the one published on the Play Store.