Senior Full-Stack Engineer (NestJS and React)

N-iX is looking for a Senior Full-Stack Engineer to join a team modernizing a large ERP/PSA platform for a US-based software company.

This role combines hands-on development with technical decision-making, with approximately 55% backend and 45% frontend work. You will build new features, explore complex business logic, and help shape the platform’s evolution using TypeScript, NestJS, React, and Azure.

Responsibilities:

• Design and implement end-to-end features using NestJS and React.
• Analyze the existing codebase, understand business workflows, and contribute to the gradual modernization of the platform.
• Design and optimize relational database schemas and queries.
• Participate in system design, architecture discussions, and technical decision-making.
• Work directly with technical and business stakeholders to clarify requirements and translate business needs into solutions.
• Ensure solutions meet security, performance, scalability, and maintainability requirements.
• Contribute to code reviews, automated testing, and CI/CD improvements.
• Identify technical risks, manage dependencies, and proactively communicate delivery concerns.
• Contribute to backlog refinement, planning, and Agile ceremonies.

Requirements:

• 5+ years of commercial software engineering experience, including backend and frontend development with TypeScript.
• Hands-on experience with NestJS and React.
• Practical experience building and integrating REST APIs and GraphQL.
• Experience developing complex backend systems with substantial business logic.
• Solid understanding of distributed systems and microservices-based architectures.
• Strong expertise in relational databases such as MySQL or PostgreSQL, including schema design, query optimization, and performance analysis.
• Hands-on experience with Apache Kafka.
• Hands-on experience with Microsoft Azure.
• Experience analyzing large legacy codebases and working with limited documentation.
• Experience contributing to system design and technical decisions.
• Strong analytical, problem-solving, and stakeholder communication skills.
• Experience working in Agile, Scrum, or Kanban teams.
• Upper-Intermediate or higher English and proficiency in Ukrainian for daily team communication.

Nice to have:

• Experience with ERP platforms, financial systems, enterprise SaaS, multi-tenant applications, or large B2B portals.
• Experience with stored procedures, database functions, and complex SQL.
• Knowledge of PHP and Microsoft SQL Server, particularly stored procedures.
• Experience reverse engineering existing systems and incrementally modernizing legacy applications.
• Experience with AI-assisted development tools such as GitHub Copilot, Claude, or Cursor.