An All-in-One Fitness OS for Gyms
LemonFit is a monthly-subscription SaaS for gyms and fitness centers. Member booking, a real-time Apple Watch heart-rate dashboard, and AI diet analysis—the three core features your members use the moment your gym subscribes. Members access it through their gym, or continue on the LemonFit app's individual plan.
Why LemonFit Is Different
Member booking · real-time heart-rate dashboard · AI diet analysis
Gyms subscribe; members continue on the LemonFit app's individual plan
Supabase live subscriptions stream group heart rate with no polling
B2B2C Subscription Model
Gyms deploy it; members keep using it.
The gym subscribes
A fitness center adopts LemonFit monthly and runs member booking, the real-time heart-rate dashboard, and AI diet analysis.
Members use it via their gym
Registered members get booking, Apple Watch heart-rate sessions, and AI diet analysis at no extra charge.
Switch to an individual plan
Members who aren't at a gym, or who cancel, continue on the LemonFit app's individual subscription with their diet and workout history intact.
Core Features
Member booking, a real-time heart-rate dashboard, and AI diet analysis — the three your members use the moment your gym subscribes.
Member Booking
Member Booking · Reservation
Members browse schedules, book classes, and pay. Operators manage members, passes, and schedules from the reservation dashboard (Next.js + shadcn/ui). Supports Toss Payments and Apple/Google in-app purchase.
- Class schedule browsing, booking creation and cancellation
- Pass purchase — Toss Payments · Apple/Google IAP
- Booking approval/rejection workflow (admin dashboard)
- Unified member, pass, and attendance management
- React Big Calendar scheduling UI
- ApexCharts revenue, booking, and attendance analytics
Image coming soon
Real-time Heart Rate Dashboard
Live Heart Rate · Apple Watch
A web dashboard that shows the heart rate of Apple Watch-wearing members live during group class. Built on Supabase real-time subscriptions (no polling), it classifies zones (Rest, Warm-Up, Target, Peak) and ranks members by points.
- Live group heart rate on screen (up to 10 in a grid)
- Heart-rate zones — Rest / Warm-Up / Target / Peak in real time
- Points and leaderboard based on time in the target zone
- 60-point 1-minute sparkline + average & max BPM
- Supabase Postgres real-time subscriptions (no polling)
- Member/guest identification and connection status
Image coming soon
LemonFit App — AI Diet Analysis
LemonFit App · iOS & watchOS
The core feature of the LemonFit iOS/Apple Watch app. Snap a food photo or type a meal, and a proprietary AI recognizes the food and breaks down calories and nutrition. Calories in/out, workout logs, and Apple Watch session results all live in one place.
- AI diet analysis — photo capture or text entry
- Nutrition breakdown — calories, protein, carbs, fat + sodium, potassium, phosphorus
- Daily energy summary: calories in vs. out
- Strength training log (exercise, sets, reps, weight)
- Apple Watch heart-rate session results + HealthKit
- Native SwiftUI app for iOS 16+ / watchOS 10+
Image coming soon
Tech Stack
A production-ready multi-platform architecture.
Next.js 16 + Supabase Realtime
Real-time heart-rate dashboard — React 19 with Supabase Postgres live subscriptions for polling-free group sessions
SwiftUI (iOS + watchOS)
Native LemonFit app — HealthKit, StoreKit 2, and WatchConnectivity unify diet, heart rate, and subscriptions
Proprietary AI diet service
An in-house AI service that recognizes food from photos or text and analyzes calories and nutrition (GCP Cloud Run)
Rust · Axum backend + Toss Payments
Seoul-region GCP Cloud Run health-api — auth, meals, subscriptions + Toss Payments / Apple & Google IAP
Coming Soon — InBody Integration
Bringing InBody device measurements into the platform. Trainers will see body composition + workout data in a single view; members will review InBody history alongside their exercise records.
InBody Webhook/Pull API — body fat %, muscle mass, segmental lean data
Admin dashboard — per-member InBody history and trend charts
Member app — InBody measurement history in My Page
Phase 2: program recommendation engine based on body composition
Gym & Fitness Center Plans
Run LemonFit for your location on a monthly subscription. The TV display and instructor controller apps are not included.
Included
- Member booking — class scheduling, reservations, passes
- Real-time heart-rate dashboard — Apple Watch group sessions, zones, ranking
- LemonFit app AI diet analysis — photo/text nutrition analysis
Not included
- TV display app (class video playback)
- Instructor controller app (TV remote control)
Starter
AI diet analysis only
Per gym location · plus applicable tax · cancel anytime
- LemonFit app AI diet analysis — free for all members at the location
- Member meal logging + nutrition analysis reports
- Admin account + unlimited member accounts per location
- Email technical support and onboarding assistance
- Member booking & heart-rate dashboard available on higher plans
Standard
Member booking + AI diet analysis
Per gym location · plus applicable tax · cancel anytime
- Member booking — scheduling, reservations, passes, attendance
- LemonFit app AI diet analysis — free for all members at the location
- Admin reservation dashboard + revenue & attendance analytics
- Toss Payments · Apple/Google IAP integration
- Unlimited member accounts per location
- Email technical support and onboarding assistance
Pro
RecommendedEverything in Standard + real-time heart rate
Per gym location · plus applicable tax · cancel anytime
- Everything in Standard
- Real-time heart-rate dashboard — Apple Watch group sessions
- Heart-rate zones, points, leaderboard, and session results
- Supabase real-time live updates (no polling)
- Unlimited member & instructor accounts per location
- Priority technical support and onboarding assistance
Members who aren't at a gym, or who cancel, can keep their diet and workout history on the LemonFit app's individual subscription (₩4,400/mo with a 7-day free trial, or ₩33,000/yr).
Payments are processed securely via Stripe. For multi-location or franchise-wide deployments, contact us.
Inquire About LemonFit
Let's launch a subscription SaaS for your gym or fitness center — member booking, a real-time heart-rate dashboard, and AI diet analysis, delivered together.