Onsite Full Stack Engineer (Node.js / React) – Fintech

At ArrowFin, we support the construction and optimization of high-performance technology solutions that power our clients' trading activities directly on the Chicago Mercantile Exchange (CME). We develop our own software—no outsourcing or third-party client work—backed by an engineering team focused on real-time systems and distributed architecture.

Role

We are hiring an Onsite Mid-Level Full Stack Engineer (Node.js / NestJS + React) for our office in El Poblado, Medellín. You will ship production code for our real-time trading products, working closely with senior engineers who will support your growth.

Key Responsibilities

• Full Stack Development: Build and maintain backend services and REST APIs with Node.js, TypeScript and NestJS, and modern frontend interfaces with React and TypeScript.
• Quality: Write unit, integration and E2E tests as part of every deliverable, and take part in code reviews.
• Data & Real-Time: Write efficient PostgreSQL queries and migrations, respect multi-tenant data isolation, and work with WebSocket-driven UI updates.
• Collaboration: Turn technical specs into working features, raise blockers early, and help troubleshoot staging and production issues with the team.

Required Stack & Qualifications

Hard Requirements

• Location & Language: B2 or higher English proficiency. Based in or around Medellín, or open to relocating (onsite role).
• Experience: 2–4 years of professional full stack web development.
• Backend: Solid experience with Node.js and TypeScript, ideally with NestJS (REST APIs, modules, dependency injection, guards and pipes).
• Frontend: Strong React + TypeScript skills, plus hands-on experience with React Router and TanStack (Query / Table / Router).
• Database: Working knowledge of PostgreSQL (queries, indexing basics, migrations with Prisma, TypeORM or Flyway).
• o   Testing: Habit of writing tests (Jest/Vitest, Supertest, React Testing Library; Playwright is a plus).

Nice to Have

• Experience with Java and Spring Boot. We run a polyglot backend and some services use Spring.
• Exposure to WebSockets or event-driven systems.
• Familiarity with Clean / Hexagonal Architecture.
• Background in Fintech, trading, or other regulated environments.
• Docker and basic observability tooling (Grafana, Prometheus).