Lumnix

About the Client

Global FinTech startup,  is building a modern financial intelligence platform that helps teams analyze performance, forecasts, and operational metrics across time. The product is data-heavy, highly interactive, and correctness-driven. Accuracy, transparency, and trust are core principles.

We are early-stage but live, with real customers and real financial data. We move fast, but we do not break fundamentals.
 

Role Overview

We are looking for a Senior Fullstack Engineer to help design, build, and evolve core product functionality across frontend, backend, and data layers.

This is a hands-on role with real ownership. You will work closely with Product, QA, and other engineers to deliver features end-to-end, from API design to UI behavior to data correctness.

This role is not about managing people. It is about shipping high-quality software in a complex, data-driven environment.
 

What You Will Do

• Design and build end-to-end product features, from UI to backend logic to database interactions
• Implement and evolve core workflows, including:
  • Data ingestion and connector management
  • Metrics configuration and overrides
  • Time-based grouping (daily, weekly, monthly, quarterly, yearly)
  • Forecasting, reporting, and analytics views
• Design, build, and maintain NestJS-based backend services and integrations, including API endpoints, domain logic, data validation, and integration workflows
• Work within a modular monolith backend, contributing to shared domain logic and internal service boundaries
• Write efficient, readable SQL for data retrieval, aggregation, and validation
• Ensure correctness of financial calculations and aggregations
• Collaborate closely with:
  • Product on requirements and edge cases
  • QA on testability and bug resolution
  • Other engineers on architecture and code quality
• Review code and contribute to technical standards and best practices
• Participate in release planning and production readiness
   

Required Skills & Experience

• 5+ years of professional software engineering experience
• Strong experience building fullstack web applications
• Strong backend experience with Node.js-based API services, including business logic and data validation
• Strong SQL skills (required):
• Solid frontend experience with:
  • React
  • TypeScript
  • Modern component-based UI patterns
• Writing complex queries
• Aggregations and joins
• Reasoning about data correctness and performance
• Experience working with relational databases (PostgreSQL preferred)
• Comfort working in production systems with real users and 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 working in early-stage or startup environments
• Exposure to Python is a plus, but the core backend is implemented in Node.js
   

What Success Looks Like in the First 90 Days

• You understand client’s data model and core product flows
• You ship multiple production features end-to-end
• Your code is readable, testable, and trusted by the team
• You proactively surface edge cases and data issues

Product and QA rely on you for clarity and execution