Middle Full-Stack Engineer (Node.js+React)

N-iX is looking for a Middle Full-Stack Engineer (Node.js and React) to join our team!

Our client is a London-based fintech startup developing a digital marketplace for the secondary private credit market. The platform enables institutional investors to buy and sell credit positions, participate in co-investments, access liquidity before loan maturity, and leverage AI-powered insights, including automated deal summaries and fair asset valuations. The project involves building and enhancing the platform with a dedicated full-stack engineering team, covering backend development (distributed systems and multithreading), frontend development (UX/UI), and cloud infrastructure and observability (AWS, Datadog, Prometheus, and CI/CD).

Responsibilities:

• Ensure high-quality delivery covering both functional and non-functional requirements (security, performance, scalability etc)
• Participate in technical discussions and own key technical decisions, ensuring solutions are aligned with best practices
• Design and implement end-to-end features across frontend and backend in a fast-paced environment
• Communicate effectively with both technical and non-technical stakeholders from the client side on a daily basis
• Refine requirements, manage dependencies, and contribute to backlog prioritization and planning
• Engage independently with stakeholders to translate business needs into working solutions
• Contribute to platform improvements and technical strategy
• Drive engineering quality by reviewing code, contributing to testing and CI/CD, etc.

Requirements:

• 3+ years of commercial experience as a Full-Stack Developer.
• Strong expertise in JavaScript/TypeScript with proven experience building web applications using React, Next.js, Styled Components.
• Solid backend experience with Node.js, databases (MariaDB/MySQL, DynamoDB, MSSQL, ElasticSearch), and GraphQL.
• Knowledge of AWS (Lambda) and microservices architecture.
• Hands-on involvement in CI/CD, QA, and testing activities.
• Upper-Intermediate+ English proficiency.
• Comfortable working independently and engaging directly with stakeholders to clarify requirements.

Nice to Have:

• Experience in fintech or credit/loan-related platforms.
• Familiarity with observability tools (Datadog, Prometheus).
• Exposure to distributed systems and multi-threading.
• Strong understanding of performance and scalability challenges in financial systems.