Middle+ Back-End Developer (Slots) - iGaming/Casino

Employment: Full-time

Salary: $2,800–3,500 net (depending on interview results and experience)

Probation Period: 1 month (salary during probation depends on the candidate's actual range)

About the Project

We're building a slots game engine on a modern Node.js stack: round state machine, provably-fair mechanics, and reliable transactional logic for a multi-currency financial platform. The challenges revolve around deterministic computation, money-calculation precision, and balance consistency under load.

Our Tech Stack

Node.js · TypeScript · Fastify · PostgreSQL · WebSocket/Socket.IO · Firebase Auth · Provably Fair (HMAC-SHA256) · BigInt · Docker

Responsibilities

• Design the game engine using Node.js, TypeScript, and Fastify: round state machine, outcome taxonomy, autoplay, bet cancellation.
• Implement Provably Fair (HMAC-SHA256) with server-side generation and verification, plus BigInt arithmetic for money calculations.
• Develop the wallet and transactions: multi-currency support, deposits/withdrawals, idempotency, balance consistency.
• Build platform logic: KYC, VIP levels, affiliate program, leaderboards, notifications.
• Integrate an external betting API (Axios: auto-refresh, circuit breaker), real-time layer (WebSocket/Socket.IO), and authorization via Firebase.
• Work with PostgreSQL and containerization (Docker/Compose); cover critical logic with tests.

Requirements (must-have)

• 3+ years of back-end development experience with Node.js and TypeScript (Fastify/Express preferred).
• Experience designing transactional logic (balances, payments, idempotency) and working with PostgreSQL.
• Understanding of deterministic computation and money-calculation precision (BigInt / decimal), state machines.
• Experience integrating external APIs and real-time communication.
• Middle+: autonomy, testing, code review, attention to security.
• Experience in iGaming/Casino, provably-fair/cryptography (HMAC-SHA256), RNG mechanics.

Nice to Have

• Firebase Auth (2FA TOTP), experience with KYC/AML, VIP/affiliate systems.
• Familiarity with regulated betting and high-load financial systems.