Senior Fullstack Engineer

Lumnix is an early-stage global FinTech startup building a modern financial intelligence platform for analyzing performance, forecasts, and operational metrics. We seek a Senior Fullstack Engineer to design, build, and evolve core product functionality across frontend, backend, and data layers in a hands-on role with real ownership.

Main Responsibilities:

• Design and build end-to-end product features from UI to backend logic to database interactions
• Implement and evolve core workflows including data ingestion, connector management, metrics configuration, time-based grouping, forecasting, reporting, and analytics views
• Design, build, and maintain NestJS-based backend services and integrations with API endpoints, domain logic, data validation, and integration workflows
• Write efficient SQL for data retrieval, aggregation, and validation while ensuring correctness of financial calculations
• Collaborate closely with Product, QA, and engineering teams on requirements, testability, architecture, and code quality
• Review code, contribute to technical standards, and participate in release planning and production readiness

Required:

• 5+ years of professional software engineering experience
• Strong experience building fullstack web applications
• Strong backend experience with Node.js-based API services, business logic, and data validation
• Strong SQL skills including complex queries, aggregations, joins, and data correctness reasoning
• Solid frontend experience with React, TypeScript, and modern component-based UI patterns
• Experience with relational databases (PostgreSQL preferred)
• Comfort working in production systems with real users and financial data
• Ability to reason about edge cases, failure modes, and data consistency

Nice to Have:

• Experience with financial, analytics, or reporting platforms
• Familiarity with React-based frontends
• Exposure to PostgreSQL or similar relational databases
• Experience in early-stage or startup environments
• Python exposure

This is a hands-on role focused on shipping high-quality software in a complex, data-driven environment. Not a management position. Work involves designing and building end-to-end features across multiple layers of a data-heavy, highly interactive platform with real customers and real financial data.