Principal Integration Engineer Architect (JavaScript/Python)

About the client

Our client is looking for a hands-on Principal Integration Engineer & Architect to lead the design, evolution, and execution of our core data integration ecosystem. This role is built specifically for an elite technical leader who loves mapping out highly reliable distributed architectures but is driven by a strong desire to stay close to the metal- allocating approximately 70% of their time to writing mission-critical production code, core libraries, and internal SDKs, and 30% to high-level architectural design, API contract governance, and technical mentorship. 
Our client is a venture-backed AI-powered platform built specifically for consumer brands. It connects to sources like banks, POS systems, and advertising platforms to deliver daily profit & loss snapshots, cash flow plans, and peer benchmarking - all in real time. With integrations across finance, e‑commerce, and marketing tools, Iris provides the clarity and automation brands need to grow confidently 
 

What You’ll Do
 

• Write Foundational Code (70% Focus): Maintain a heavy, hands-on presence in the codebase. Author core integration libraries, internal SDKs, and high-performance data transformation engines in JavaScript (Node.js/NestJS) and Python to establish gold standards for the engineering team.
• Architect for Scale (30% Focus): Design and evolve a robust, multi-tenant integration architecture capable of handling data streams from hundreds of distinct third-party platforms concurrently.
• Build for Resilience: Establish bulletproof integration patterns to successfully navigate external API limitations, handling advanced OAuth state machines, dynamic webhook processing, elegant rate-limiting, sophisticated retries, and distributed tracing.
• Govern API & Data Integrity: Define and enforce strict schema validations, transaction boundaries, and end-to-end data transformation standards to guarantee accurate real-time financial reporting.

• Technical Leadership & Mentorship: Act as an elite technical sounding board for the engineering organization. Conduct comprehensive architecture reviews, upskill senior engineers, and champion modern DevOps, testing, and deployment workflows.Design, implement, and maintain core backend services using JavaScript and Python.

  
   

What We’re Looking For

• Deep Industry Experience: 8+ years of professional software engineering experience, with a proven history of designing, deploying, and maintaining high-throughput, distributed back-end integration solutions.
• Polyglot Mastery: Highly proficient in both JavaScript/TypeScript (Node.js, NestJS) and Python, knowing exactly when and where to leverage each language's native strengths.
• Advanced Integration Expertise: Extensively experienced interfacing with chaotic external REST/GraphQL APIs, webhooks, asynchronous event queues, and state management systems under high volumes.
• Data Modeling & Schema Excellence: Expert-level understanding of relational (SQL) and non-relational (NoSQL) databases, schema design, complex data validation, mapping workflows, and ETL pipeline design.

• True Builder Mentality: A strong architectural thinker who actively rejects the "ivory-tower" approach and remains deeply passionate about shipping high-quality production code every single week.
  
  Would Be a Plus

   

• Direct technical experience within FinTech, e-commerce SaaS platforms, or real-time data streaming architectures (e.g., Kafka, RabbitMQ).
• Familiarity with financial data aggregates or banking networks (e.g., Plaid, Yodlee, Stripe).
• Experience setting up data ingestion pipelines optimized for downstream AI/LLM analysis models.
   

What We Offer

• Competitive salary aligned with market standards, with annual salary reviews.
• A friendly, collaborative startup environment where you can drive impact in a mission-critical space for growing consumer brands.
• High-growth opportunity - join early and help shape a cutting-edge product used by high-velocity, finance-driven companies.
• Access to modern tech stack, including serverless/cloud-native solutions, event-driven pipelines, and experimentation with LLMs/AI for data validation.
• Generous time off, flexible work arrangements, and commitment to work-life balance.

About LumnixLumnix is a boutique technology talent agency that connects businesses with exceptional technology professionals from around the world. We specialize in sourcing, vetting, and managing top-tier remote talent to help startups and enterprises build high-performing, distributed technology teams.