Overview
A growing gym chain needed to replace their outdated key fob access system and manual front-desk membership sales with a modern, automated solution. Members were frustrated with lost fobs, long queues during peak hours, and limited payment options for walk-ins.
We designed and built an end-to-end system combining custom hardware with a mobile app and admin dashboard. Members use QR codes generated in the app to unlock gym doors instantly. Walk-in customers and day-pass buyers use self-service kiosks equipped with coin and bill acceptors to purchase memberships or single-visit passes without staff assistance.
Challenges
Replacing Legacy Access Control
The existing key fob system was expensive to maintain, fobs were frequently lost or shared between non-members, and there was no way to revoke access in real time.
Unattended Membership Sales
The gym wanted to sell day passes and memberships 24/7 without requiring front-desk staff, especially during early morning and late-night hours.
Cash Payment in a Digital System
A significant portion of walk-in customers preferred paying with cash (coins and bills in EUR), requiring hardware integration alongside digital payment flows.
Multi-Location Management
The system needed to work across three separate gym locations with centralized member management, access rules, and revenue reporting.
Reliable Offline Operation
Gym doors must open for valid members even during internet outages. The access system cannot depend on constant cloud connectivity.
Solution
Mobile App with Dynamic QR Codes
Built a cross-platform mobile app where members register, manage their membership, and generate time-limited QR codes for gym entry. QR codes rotate every 30 seconds to prevent screenshots or sharing.
QR Scanner Hardware at Entry Points
Installed custom QR scanner units at each gym door connected to an access controller. On valid scan, the door unlocks in under one second. Invalid or expired codes are rejected with clear feedback on the scanner display.
Self-Service Kiosk with Cash Acceptor
Deployed kiosks with integrated coin selector and bill validator (EUR) at each location. Walk-in users select a membership type or day pass, insert cash, and receive a printed QR code receipt for immediate entry. The kiosk also supports card payments.
Centralized Admin Dashboard
Built a web-based admin panel for gym staff to manage members, view access logs across all locations, configure pricing, monitor kiosk revenue, and handle membership suspensions or cancellations in real time.
Offline-First Access Control
The door controllers cache valid member lists locally and sync with the server periodically. During outages, members with cached credentials can still enter. All access events queue locally and sync when connectivity restores.
Technologies Used
Results
Eliminated Front-Desk Dependency
All three locations now operate 24/7 without requiring reception staff for access or membership sales, significantly reducing operational costs.
30% Increase in Walk-In Memberships
Self-service kiosks with cash acceptance removed the friction of walk-in sign-ups, leading to a measurable increase in new memberships from casual visitors.
Zero Unauthorized Access
Rotating QR codes eliminated fob sharing and unauthorized entry. Every access event is logged with member identity, timestamp, and location.
Sub-Second Door Response
QR scan to door unlock happens in under one second, providing a smooth and frustration-free entry experience for members.
Centralized Revenue Visibility
Gym owners have real-time visibility into kiosk cash collections, digital payments, and membership revenue across all locations from a single dashboard.
99.8% Uptime Including Outages
Offline-first architecture ensures doors remain operational even during network disruptions, with zero reported access failures since launch.