flock.spot - Privacy-First Family Location Sharing

Target Launch: February 2025 Status: App functional, background location blocker being worked on

Tagline: "Your family. Your location. Nobody else."

Problem

Life360 dominates family location sharing (80M+ users) but sells precise location data — including children's locations — to data brokers. Lawsuits, breaches, and a business model built on monetizing family movements.

Parents face impossible choice: sacrifice privacy for peace of mind, or go without.

Solution

Family location app with end-to-end encryption using Nostr protocol (NIP-44, audited by Cure53). We literally cannot see where your family is — only family members hold the decryption keys.

No ads. No data selling. No central database to breach.

Target Users

• Privacy-conscious parents (30-50) with kids aged 8-18
• Families with elderly members needing monitoring
• Close friend groups wanting private sharing
• People who read privacy policies and care

Current State (from repo)

Working:

• ✅ Expo (React Native) mobile app
• ✅ Nostr protocol integration with nostr-tools
• ✅ NIP-44 end-to-end encryption
• ✅ User identity (personal Nostr keypair in SecureStore)
• ✅ Flock identity (shared group secret for encryption)
• ✅ Live location sharing on map (MapLibre)
• ✅ Family circles (create, join, invite)
• ✅ Password-protected invite codes (v2 format)
• ✅ DM invites with NIP-17 gift wrapping
• ✅ Tamagui UI framework with dark/light themes
• ✅ Self-hosted strfry relay with whitelist
• ✅ Subscription sync service (Apple/Google IAP)
• ✅ Landing page (landing/)
• ✅ Security fixes applied (Jan 2025)
• ✅ Foreground location sharing

The Blocker - Background Location:

• ❌ Background location when app force-quit (iOS)
• Current: Location.startLocationUpdatesAsync() - stops if force-quit
• Needed: Location.startGeofencingAsync() - rolling geofence approach
• Life360's approach: 500m+ geofence → exit triggers relaunch → new geofence
• Trade-off: Less accurate (100-500m) but survives force-quit
• Status: Paul actively working on this

Pending for launch:

• [ ] Background location solution (blocker)
• [ ] Security hardening (see below)
• [ ] App Store / Play Store submission
• [ ] Production relay deployment

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                    Mobile App (Expo/React Native)                │
│  • User keypair (SecureStore)  • Flock shared secret            │
│  • NIP-44 encryption before sending  • MapLibre rendering       │
└─────────────────────────────────────────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                          Caddy (reverse proxy)                   │
│  relay.flock.spot → strfry:7777   api.flock.spot → sync:3000    │
└─────────────────────────────────────────────────────────────────┘
         │                                    │
         ▼                                    ▼
    ┌─────────────┐                    ┌─────────────┐
    │   strfry    │                    │    sync     │──► SQLite
    │   (relay)   │◄── whitelist.lua ──│  (service)  │
    └─────────────┘                    └─────────────┘

Cryptographic Model (Two-Key):

1. User Identity: Personal Nostr keypair, signs all events
2. Flock Identity: Shared group secret for NIP-44 encryption

Relays see encrypted blobs, not locations. Even relay operators can't see family locations.

Tech Stack

Layer	Technology
Mobile	Expo (React Native)
UI	Tamagui ("warm minimalism")
Maps	MapLibre React Native
Protocol	Nostr (decentralized)
Encryption	NIP-44 (ChaCha20 + HMAC-SHA256, Cure53 audited)
Relay	strfry (self-hosted) + Caddy
Sync Service	Node.js + SQLite
Payments	Stripe (US external), App Store/Play Store (RoW)

Infrastructure cost: ~€10/month for 5,000+ families

Revenue Model

€4.99/month or €49/year per family (unlimited members)

No free tier with ads. Business model is subscriptions, not data.

US customers: External checkout (0% Apple commission post-April 2025 ruling) Rest of world: App Store / Play Store

Business Projections

Milestone	Target
Month 3	1,000 paying families
Month 6	5,000 paying families
Month 12	20,000 paying families
Year 1 ARR	~€1M

Competitive Positioning

	Life360	flock.spot
End-to-end encrypted	❌	✅
Can see your location	✅ They can	❌ Only family
Sells data	✅ To data brokers	❌ Never
Central database	✅ Breach target	❌ Decentralized
Price	€8-25/mo	€4.99/mo

Security Status

Completed (Jan 2025):

• ✅ Password-protected invite codes (NIP-44)
• ✅ DM invites with NIP-17 gift wrapping
• ✅ Memory leak fix in DM polling
• ✅ Race condition fix in relay reconnect
• ✅ Storage health tracking

Pending (from SECURITY_TODO.md):

• [ ] Rate limiting on /register (High)
• [ ] Auth token for /update-pubkeys (High)
• [ ] Apple JWS full verification (Medium)
• [ ] Google Pub/Sub verification (Medium)
• [ ] Request body size limit (Medium)

MVP Features

Feature	Status
Live location	✅ Working
Private circles	✅ Working
Place alerts	❌ Not started
Location history	❌ Not started
SOS button	❌ Not started

Key Risks

Risk	Mitigation
Background location (iOS)	Rolling geofence approach (in progress)
App store rejection	Privacy-first positioning helps, not gaming system
Life360 response	First mover on privacy, different market segment
Trust building	Open about encryption, Nostr is open protocol

Blockers

• CRITICAL: Background location when phone locked/force-quit
  • iOS: Only geofencing survives force-quit
  • Solution: Rolling geofence (500m+) like Life360
  • Paul actively working on this

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Validation Scores

Criterion	Score	Notes
Competition	4/5	Life360 dominant but privacy scandals create opening
Willingness to Pay	4/5	Parents pay for kids' safety, €4.99 < Life360
Feasibility	3/5	App 80% done, background location is hard
Privacy Angle	5/5	Privacy IS the entire product
Personal Interest	?/5	TBD
Total	16+/25	Solid, but feasibility risk from blocker

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Links

• Repo: /Users/paulspende/Documents/paul/repos/flock-spot
• App: /app (Expo React Native)
• Relay: /relay (strfry + sync service)
• Landing: /landing (static site)

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Progress Log

• 2025-01-05: Brief updated with comprehensive repo review
• 2025-01-05: Background location identified as critical blocker
• 2025-01-05: Security fixes completed (invite encryption, relay reconnect)
• 2025-01-05: App architecture well-developed, near production-ready