eJago

Case Study — Sports Tech / Golf

HelloCaddy

📍 United States + Korea 📅 2026 ⏱ Pre-launch build 🔗 hellocaddy.net ↗
Mobile App DevelopmentAI IntegrationHardware-Software IntegrationGPS Course MappingCart Rental ActivationFlutter + Swift + Kotlin

The most comprehensive golf scoring and friendly competition app ever built. Real course maps and data across 8,400+ courses in the US and Korea. Integrated cart rental activation. AI swing analysis from a wearable belt sensor. One app, zero friction.

8,400+
Golf Courses Mapped
US + Korea, full GPS data
18K+
Pre-Launch Downloads
iOS + Android combined
3
Core Product Surfaces
App, Cart Rental, Belt Sensor
1 App
Replaces 4 Standalone Tools
Scoring, GPS, Rental, Leaderboards

The Problem

Golfers Were Jogging in Place

Golf tech is fragmented. GPS apps handle scoring in isolation. Cart rentals require a separate app. Swing analysis is yet another subscription. Course data lives in five different databases — none of them talking to each other.

There are 24 million golfers in the US alone. The average golfer plays 7 rounds per year and pays $50–$120 per round. Yet nobody had built the operating system for the sport — just a pile of disconnected apps.

The Score Caddy hardware (wearable belt sensor predicting swing distance and ball flight) had no companion app. The robotic HelloCaddy ME cart had no rental activation flow. Both existed as hardware with no software layer connecting them to the golfer.

The Solution

One App. Every Shot. Every Round.

HelloCaddy isn't a scoring app. It's the operating system for golfers — connecting GPS course maps, real-time scoring, friendly competition leaderboards, cart rental activation, and AI swing analysis into one seamless experience.

  • → Real-time GPS scoring with hole-by-hole tracking and round summaries
  • → 8,400+ course maps with yardage, hazards, and green elevations across US and Korea
  • → Integrated cart rental activation — unlock and pay for HelloCaddy ME carts directly in the app (works like Bird scooter rental)
  • → Score Caddy belt sensor integration — wearable AI predicts swing power, ball carry distance, and distance to the hole
  • → Friendly competition leaderboards — weekly tournaments among friends and club members
  • → Swing points analytics — track your improvement across rounds and club choices

Product Architecture

Three Surfaces. One System.

📱
01

HelloCaddy App

  • → iOS + Android native apps
  • → 8,400+ course GPS maps (US + Korea)
  • → Real-time scoring + round replay
  • → Friendly competition leaderboards
  • → Club recommendations by distance
  • → Swing points history + analytics
🛺
02

Cart Rental Activation

  • → QR/Bluetooth cart unlock
  • → Per-minute and flat-rate pricing
  • → Works like Bird — tap, ride, drop
  • → Fleet management for courses
  • → Real-time cart GPS + battery
  • → Payment via Apple Pay / Google Pay
🎯
03

Score Caddy Belt Sensor

  • → Wearable belt with IMU sensors
  • → Swing power + ball carry distance
  • → Club selection recommendation
  • → Distance-to-hole calculation
  • → Real-time shot tracking
  • → Post-round AI swing analysis

Technical Architecture

Built for Real-Time Performance

GPS course data processing, real-time cart telemetry, and IMU sensor fusion from a wearable — all requiring sub-second response times and offline-first reliability on the course.

MOBILE APP STACK
iOS: Swift + SwiftUI
Android: Kotlin + Jetpack Compose
Course Maps: Mapbox + custom tile layers
BLE: CoreBluetooth (belt sensor pairing)
State: Riverpod + Real-time sync
BACKEND + INFRA
API: FastAPI + Python
Real-time: WebSockets (cart telemetry)
Course DB: PostgreSQL + PostGIS
IMU Fusion: On-device ML (CoreML/TFLite)
Cart BLE: ESP32 firmware stack
Payments: Stripe + Apple/Google Pay

Course Data

8,400+ Courses.
Two Countries.

Every course in the US and Korea has been mapped with GPS coordinates, hole yardages, hazard locations, green shapes, and elevation data — all verified and updated by a dedicated course data team.

United States
All 50 states — public, private, resort
7,200+ courses
Korea
Full KLPGA and K巡 tournament data
1,200+ courses
Data per course
Hole yardages, fairway shapes, green elevation, hazards
18 data points
Update cadence
Course changes tracked via golfer reports + satellite imagery
Quarterly refresh
⛳
8,400+
Mapped Golf Courses
🇺🇸 US
7,200+ courses
🇰🇷 Korea
1,200+ courses

Deliverables

What We Delivered

✅ Native iOS App
Swift + SwiftUI — full scoring, GPS maps, leaderboards, cart unlock. Live on App Store.
✅ Native Android App
Kotlin + Jetpack Compose — Play Store listing. BLE pairing with Score Caddy belt.
✅ Cart Rental Activation Flow
BLE + QR-based cart unlock. Works exactly like Bird — find cart, tap, ride. Fleet backend included.
✅ Score Caddy Belt Integration
IMU sensor fusion (accelerometer + gyroscope). On-device ML predicting ball carry distance. Bluetooth LE pairing protocol.
✅ Course Database Architecture
PostgreSQL + PostGIS for geospatial course data. 8,400+ courses, 18 data points per hole. Quarterly refresh pipeline.
✅ Real-time Cart Telemetry
WebSocket server for live cart GPS, battery level, and ride status. Fleet dashboard for course operators.
✅ Competition Leaderboard Engine
Per-course, per-club, and friend-group leaderboards. Weekly tournament scoring with auto-updates.
✅ Payment Integration
Stripe for cart rental billing. Apple Pay + Google Pay in-app. Subscription for premium scoring tier.
✅ Pre-Launch App Store Setup
iOS App Store + Google Play Store listings, screenshots, ASO keywords, and launch-day review preparation.

Building a Sports Tech Product?

Whether it's a scoring app, hardware integration, or a rental platform — we build products that golfers actually want to use.

Book Your Free Strategy Call

Let's Talk

Start Your Project

Fill out the form or book a call directly →

Prefer to Talk Now?

Book a free 30-min strategy call — no pitch, just results.

Or Reach Us Directly

Email

hello@ejago.com

Location

Los Angeles, CA

Hours

Mon–Fri, 9AM–6PM PST