Oleksandr Riasnyi

Founder · Full-stack Developer

I'm building FITGYM — a multi-tenant SaaS CRM for Ukrainian fitness clubs: memberships, class booking, QR access control and payments, with a client mobile app and a web admin/owner panel sharing one REST API. First pilot — Berdychiv Sky, a real local club the system is configured for.

By day I'm a sysadmin & programming instructor @ IT STEP Academy, Berdychiv (Windows fleet, MikroTik / RouterOS networking, video surveillance); the rest of the time I ship FITGYM end-to-end — from Django REST APIs to React Native apps, deployment and CI/CD.

🎓 Software Engineering @ Berdychiv College — graduating 2026. 🌱 Going deep on multi-tenant SaaS architecture, payments and distribution.

Backend

Frontend & Mobile

Infrastructure & Tools

FitGym CRM → — a multi-tenant B2B SaaS for local fitness clubs. Not a course project — an active venture: memberships, class booking, QR-based access control and payments, a client mobile app and a web owner panel on one REST API. First pilot: Berdychiv Sky.

Highlights

• 🏢 Multi-tenant gym isolation — every query is scoped to the user's club; fail-closed, no cross-tenant leaks.
• 📲 Signed QR check-in — the app generates an HMAC-signed QR pass; a scanner validates access with a green/red result.
• ⏰ Time-limited subscriptions — e.g. a Morning Pass valid only 08:00–13:00 in the gym's timezone, enforced at the door.
• 💳 Per-gym payments — each club connects its own LiqPay merchant (encrypted keys); the platform charges a flat subscription, not a cut of transactions.
• 🧾 Staff audit log — append-only trail of who did what (sales, wallet edits, settings), for owner transparency.
• 🌐 White-label — each club gets its own branded landing (subdomain or custom domain) and client app.