# Senior Fullstack Developer (NestJS/ React.js)

**Company:** [Symphony Solutions](http://jobs.workable.com/companies/9o3HSXG1digSEp5ARNTfZQ.md)
**Location:** Remote
**Workplace:** remote
**Employment type:** Full-time
**Department:** ___

[Apply for this job](http://jobs.workable.com/view/623a2480-1ba1-4c86-a7ea-54c7284553c0)

## 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.

## Requirements

-   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.