GymOS — Multi-Tenant SaaS for Gyms & Fitness Studios

Gympify's membership billing engine runs on Stripe Subscriptions with a configurable dunning sequence for failed payment recovery: failed payments trigger automatic retries on days 3, 7, and 14 using Stripe's Smart Retries algorithm, which selects retry timing based on card network data for optimal success rates. On final failure, the member's access is automatically suspended — their QR code check-in stops working — and a reactivation link is sent to their registered email. This automated dunning cycle recovers an estimated 15–20% of initially failed renewals without staff intervention.

The class booking engine enforces per-class capacity limits, per-member booking windows (how far in advance members can book), and a configurable waitlist queue. When a booked member cancels within the late cancellation window, the system automatically offers the slot to the next waitlisted member via push notification — and if the waitlisted member does not confirm within 30 minutes, the next member in queue is notified. Late cancellation penalties are applied automatically via Stripe through the member's saved payment method. This waitlist and penalty system reduced no-shows from 30–40% of booked capacity to under 8% in the first month post-launch.

The QR code check-in system generates a unique QR code per member that refreshes every 5 minutes using a time-based token (TOTP-style rotation) — preventing screenshot sharing or code reuse. The staff check-in app scans the QR code via device camera, validates the token against the backend, confirms the member's active membership status, and opens the turnstile or notifies the front desk in under 3 seconds. Each check-in event writes to an attendance log with timestamp, class ID, and staff device ID — providing a complete attendance history for GDPR-compliant data access requests and for the AI attendance prediction model's training data.