Central – Encrypted Chat & Personal Safety - Sell Project

Central – Encrypted messaging, personal safety and a social world in one app Central is a production-grade communication and personal-safety platform. It is live on Google Play, has gone through Google’s closed-beta review and runs on European infrastructure. It replaces what would normally be four or five separate products: an end-to-end encrypted messenger with calls, a safety and lone-worker monitoring system, a social network, a B2B guardian dashboard and a multiplayer social game. This is not a template or a prototype. It is a large codebase that took over a year of engineering, with real cryptography, real-time systems and a backend split into API and worker services. Codebase at a glance (approximate) Kotlin Multiplatform shared core: 55,000 lines. This covers networking, encryption, repositories, view models and the whole Compose Multiplatform UI, all shared between Android and iOS. Android-specific layer: 22,000 lines. This includes calls, foreground services, geofencing, widgets, the SOS Quick Settings tile, billing and FCM. iOS layer: 13,000 lines (Kotlin/Native + Swift). This includes CallKit/VoIP push, APNs, Keychain, location, SOS video, maps and StoreKit billing. The iOS app reuses the entire shared core. Central City engine: 12,900 lines of HTML5/JavaScript. It is a single isometric game engine shared by the Android app, the iOS app and the web app. Backend (FastAPI/Python): [13,000] lines, 30+ routers, Alembic migrations, test suite. Web guardian dashboard + iPhone web app: [57,000] lines. Localisation: 2 × 150 KB of string resources, plus downloadable language packs. Six languages: IT, EN, ES, DE, FR, SQ. Tech stack Mobile: Kotlin, Jetpack Compose / Compose Multiplatform, Ktor, Room (versioned non-destructive migrations), Hilt + Koin, WorkManager, Swift for iOS platform services. Backend: Python FastAPI, PostgreSQL, Alembic, WebSockets. It runs on Railway (Amsterdam) as two services: an API and a background worker with 7 scheduled loops. Real-time: WebRTC audio calls with a TURN relay (Metered), ICE buffering and call-state resync. WebSocket rooms are used for chat, whiteboards, trips and the city. Cryptography:X25519/ECDH key agreement and AES-256-GCM. Account-bound key backup (PBKDF2, client-side encrypted). Envelope encryption for groups, with key rotation on every membership change. Encrypted media and encrypted live trip positions. The server never sees destinations or coordinates. Services: Scaleway Object Storage (EU), Cloudflare (DNS/IPv6), Mapbox, FCM + APNs, Resend transactional email, Google Play Billing (consumer plans + B2B packs). Offline: an embedded SQLite database of emergency points of interest (hospitals, pharmacies, police) that works without a connection. Feature set Messaging:E2E encrypted 1:1 and group chats; voice notes, files, media, location pins. Polls, timed/ephemeral messages, scheduled messages delivered server-side, broadcast lists. Pin, block, read receipts. Shared real-time whiteboards and collaborative maps inside chats. Calls: WebRTC audio calls with call log and failure telemetry. Personal safety:One-tap SOS from a widget, the Quick Settings tile or the app, with automatic location and a 30-second front-camera video to up to 5 contacts. Daily and weekly check-ins with escalation. Geofenced safe zones, agreed by both parties. “Safe Trip”: live encrypted tracking to a destination, an offline position queue and automatic alerts if the user doesn’t arrive. Multi-device support with remote emergency logout. Guardian web dashboard:Live map, alerts with acknowledgement, 5–30 day event timeline with CSV/print export, device management, browser chat. Company module with operators, supervisors and CSV shift import. Social: photo gallery and feed with likes and comments, communities with posts and events, friend system, onboarding tour. Central City:An isometric multiplayer town where each user owns a house, earns in-game coins by using the app and decorates rooms with crafted furniture. Visits to friends’ cities by bus, a mine, a farming/professions island and minigames. Live presence of other players with privacy controls. Trust and compliance:Moderation with reports, sanctions and an in-app appeal flow. GDPR data export and account deletion. Age gate (14+), no advertising SDKs, no data sale. Business Free, Plus and Premium subscriptions via Google Play. B2B packs for companies with lone or field workers (cleaning, security, home care), sold per operator, with a 30-day trial. Domain getcentral.net, marketing site, Play Store listing and legal documents (privacy, cookies, terms) included. What the buyer gets: full source code (Android, iOS, backend, dashboard, web app); the live Play Store app; the domain and brand; infrastructure handover and documentation.