Senior Fullstack Developer (NestJS/ React.js) at Symphony Solutions

, , Poland -

Full Time

Start Date

Immediate

Expiry Date

07 Aug, 26

Salary

0.0

Posted On

09 May, 26

Experience

5 year(s) or above

Remote Job

Yes

Telecommute

Yes

Sponsor Visa

Skills

NestJS, React.js, TypeScript, Node.js, PostgreSQL, Prisma ORM, AWS, Docker, REST APIs, JWT, Redux, GitHub Actions, Jest, Redis, AI-assisted development, Microservices

Industry

IT Services and IT Consulting

Description

The company is a provider-side iGaming observability and revenue intelligence platform that sits between game providers and their operator distribution network. The platform ingests round-event data in real time, independently computes Gross Gaming Revenue (GGR), and continuously reconciles operator-reported settlements to detect revenue leakage — a problem that costs game providers millions annually in undetected FX errors, revenue-share miscalculations, and bonus misclassifications. 5+ years of total software development experience. 3+ years of production experience with React, including complex state management (Redux / Redux Toolkit, React Query, Zustand or similar). 3+ years of Node.js / TypeScript backend experience, ideally with NestJS in a production API or BFF layer. Strong proficiency in TypeScript across both frontend and backend. Hands-on experience with Prisma ORM (or comparable) and PostgreSQL, including writing performant queries and designing indexes. Solid understanding of authentication and authorization patterns: JWT (access + refresh tokens), RBAC / Guards, session security, and multi-tenant data isolation. Experience designing and consuming REST APIs in a microservices or BFF architecture, including request validation, error handling, and contract stability. Working knowledge of AWS (EC2, RDS, ElastiCache, S3, ALB, CloudWatch, Secrets Manager) and CI/CD with GitHub Actions. Familiarity with Docker / Docker Compose and basic containerised deployment workflows. Experience with unit and integration testing (Jest, Vitest, Supertest, or similar) and a habit of shipping code with tests. Strong English communication skills (B2+). Self-organised, proactive, and comfortable working in a distributed team. Proven daily use of AI-assisted development tools (Claude, Cursor, GitHub Copilot, ChatGPT) for code generation, refactoring, debugging, testing and documentation — this is a standard expectation, not optional. Comfort treating AI tools as a normal part of the engineering workflow, not as an experiment — using them to accelerate delivery, raise code quality, and remove repetitive engineering work. Ability (and motivation) to apply AI to real SDLC tasks: scaffolding NestJS modules and React components, generating and reviewing tests, debugging production-grade TypeScript, drafting technical documentation, and reasoning about migrations (e.g., BigInt financial refactors). Awareness of the limits of AI output in a regulated, financial-grade context: every AI-assisted change must be reviewed, tested, and traceable through code review and the immutable audit log. Desirable Experience working in regulated industries — ideally iGaming under UKGC / MGA, financial services, or healthcare — with awareness of GDPR, audit logging, and PII handling. Experience with financial-grade calculations: integer (BigInt) arithmetic in minor currency units, FX handling, and reconciliation logic. Experience implementing immutable audit logs, HMAC event signing, or other tamper-evident data flows. Familiarity with Redis caching patterns, query performance tuning, and N+1 query elimination. Hands-on experience with Terraform or other Infrastructure-as-Code tooling. Experience with Elasticsearch or comparable search / analytics engines. Experience with TDD and code-review-driven development. Experience with JIRA and Confluence in an Agile / Scrum environment. Background in iGaming or online gaming platforms. Responsibilities Build and harden backend on NestJS: persistent user accounts, JWT access + refresh token flow, RolesGuard, and full tenant isolation across every API endpoint. Migrate financial calculations to BigInt arithmetic in minor currency units, ensuring every GGR figure is provably correct to the cent. Wire the immutable AuditLog across onboarding, settlement, configuration, and user-management flows so every data mutation is captured and exportable as evidence. Design and implement management APIs — Operator CRUD, Provider Creation, User Management — with strict validation and role-based access. Performance work: database indexing, Redis caching strategies, and N+1 query audit/elimination. Build the provider-facing React 19 frontend: Login UI and auth flow, App.tsx modularisation, operator onboarding screens, and live revenue dashboards. Write unit and integration tests; collaborate with QA on E2E, load and UAT cycles. Actively leverage AI-assisted tools to improve efficiency across coding, testing, debugging and other SDLC activities. Resolve technical problems as they arise and bug-fix developed features. Communicate with team members and the Product team; participate in Scrum ceremonies. Mentor middle- and junior-level colleagues as required.

Responsibilities

Develop and harden a backend using NestJS with a focus on financial calculations, tenant isolation, and immutable audit logs. Build a provider-facing React 19 frontend including dashboards and onboarding screens while leveraging AI tools for efficiency.