gn33

gn33 is a fitness-studio booking platform. Members browse a class schedule, book spots against their subscription, and get reminders. Staff run the studio: classes, rosters, attendance, plans, users, and reporting.

Production runs at app.gn33.eu.

Who uses it

Role	What they do
USER (member)	Browse and book classes, manage subscriptions, review instructors, control their own privacy and notifications.
INSTRUCTOR	See rosters for their classes, mark attendance, view their own reporting dashboard.
MANAGER	Everything an instructor does, plus manage classes, series, users, locations, and moderate reviews.
ADMIN	Full control: plans, categories, difficulty levels, app settings, legal documents, CSV import, GDPR erasure.

Role changes take effect immediately, because authorities are rebuilt from the database on every request.

What it does

For members

• Sign up and sign in: a six-step signup wizard with email PIN verification, Google and Facebook social login, and optional two-factor authentication (email OTP or authenticator app).
• Classes: a calendar and an upcoming feed grouped by day, with filters (location, room, instructor, category, difficulty) and free-text search.
• Booking: one-click booking with an Undo action, multi-spot booking on unlimited plans, and a waitlist that promotes members when a spot frees up.
• Subscriptions: buy a plan online (Netopia), track entries used, and freeze a subscription for vacation or injury.
• Cancellation policy: a configurable cutoff, and a no-show and late-cancel strike system that can trigger a temporary booking ban.
• Reminders and notifications: emails, Web Push, and WhatsApp for waitlist promotion, class reminders, and cancellations, with per-channel preferences.
• Calendar sync: a live webcal:// feed, per-booking .ics downloads, and Google Calendar links.
• Reviews: star ratings and comments for instructors, gated by an attendance threshold.
• Privacy: a GDPR self-service page to export all personal data as a ZIP and to delete the account.
• Help center: a searchable in-app help section, translated into all five locales.

For staff

• Event management: create, edit, and cancel classes. Cancelling refunds bookings and emails members.
• Recurring series: weekly rules that generate classes on a rolling horizon, with room-conflict detection and "this class only" or "this and following" edits.
• Rosters and attendance: add or remove participants, mark attended or no-show, and keep a per-event audit trail.
• Reporting: attendance, occupancy, and no-show statistics with charts, per instructor or studio-wide, plus a client-side earnings calculator.
• Users: account status (enable, disable, expiry), role assignment, and profile management.
• Locations and rooms: CRUD with pictures.
• Admin settings: cutoff minutes, review threshold, waitlist toggle, reminder timing, schedule window, and strike policy.
• Data: versioned Terms and Conditions, and CSV bulk import of members and classes with a dry-run preview.

Architecture

The platform is three independent projects, each with its own git repository.

Folder	Stack	Role
gn33-app/	Java 26, Spring Boot 4.1, Maven, PostgreSQL, Flyway	REST API under /v1, scheduled jobs, email and push delivery
gn33-spa/	React 19, TypeScript 6, Vite, pnpm	Single-page frontend
gn33-deploy/	Docker Compose, Caddy	Production stack, env examples, backup script, runbook

Notable design choices

• Single origin: Caddy routes /v1/* and OAuth paths to the backend and everything else to the SPA, so production has no CORS.
• Single timezone: Europe/Bucharest, using LocalDate, LocalTime, and LocalDateTime throughout.
• Security: JWT access tokens with rotating refresh-token families, rate-limited login and 2FA, narrow projections on member-reachable endpoints, and sanitized logging of emails, phones, and tokens.
• Schema: append-only Flyway migrations, with Hibernate validating entities at boot.
• Notifications: one NotificationDispatcher fans out to email, Web Push, and WhatsApp channels.
• Deployment: immutable image tags (ghcr.io/glwnick/gn33-{app,spa} by short SHA), single app instance by design, and a migration in progress from a TrueNAS host to a Debian Docker host.

Design and localization

• Kinetic design language: a lime primary on a deep green-charcoal ink surface, with full light and dark modes and a responsive shell. The shell has an ink sidebar on desktop and a bottom navigation on mobile.
• Five locales: en, de, es, fr, and ro, with matching backend message bundles and localized email templates. English and Romanian are the actively maintained ones.
• Branding: configured through app.branding.* rather than hardcoded.