Senior Fullstack Engineer (Node/React) - AA, Remote: Colombia - Costa Rica, Fulltime.

Gorilla Logic is looking for a Senior Fullstack Engineer with strong experience in Node.js, Fastify, React, and AI development to join our team in building and enhancing our client’s web application. You will collaborate with engineers in a fast-paced Agile environment, contributing to both backend and frontend development while developing and integrating AI-powered solutions. Success in this role will be measured by your ability to combine strong problem-solving skills, self-motivation, and a solid technical foundation to drive high-quality, scalable software delivery. Responsibilities Design, develop, and maintain scalable web applications using Node.js/Fastify for backend services and React for frontend development. Design, develop, and integrate AI-powered solutions, including Retrieval-Augmented Generation (RAG) systems. Implement and optimize PostgreSQL queries and database structures for performance and reliability. Write clean, maintainable, and well-documented code following industry best practices. Participate in code reviews, providing constructive feedback to improve code quality and maintainability. Work closely with cross-functional teams, including designers, QA engineers, and product owners, to define and refine requirements. Participate in daily stand-ups, sprint planning, and retrospectives, contributing to an efficient development process. Identify and resolve performance bottlenecks, bugs, and technical debt in both backend and frontend code. Monitor application health and reliability, implementing scalability improvements as needed. Stay up to date with new technologies, frameworks, AI development practices, and best practices in full-stack development. Proactively identify opportunities to improve development processes and application architecture. Contribute to a collaborative and learning-focused team culture. Technical Requirements Strong experience with Node.js and Fastify for building scalable and efficient backend services. Strong experience with React and modern frontend development practices. Hands-on experience designing and developing Retrieval-Augmented Generation (RAG) systems. Experience with LangChain, LangGraph, and LangSmith for building, orchestrating, and evaluating AI-powered applications. Experience with modern JavaScript (ES6+) and TypeScript. Proficiency in handling asynchronous operations, event-driven architectures, and middleware. Understanding of component-based architecture, React hooks, and reusable UI patterns. Experience with responsive and cross-browser development. Experience writing and optimizing complex SQL queries and stored procedures, preferably with PostgreSQL. Experience developing AI-powered applications and integrating AI/LLM capabilities into full-stack solutions. 5+ years of experience working in Agile environments (Scrum, Kanban, or SAFe). Strong ability to collaborate with clients and stakeholders, translating business needs into technical solutions. Experience in iterative development, backlog grooming, and delivering features in a consulting capacity. Experience with unit testing, integration testing, and end-to-end testing using Jest, Mocha, Cypress, or similar frameworks. Familiarity with test-driven development (TDD) and best practices for writing maintainable code. Bonus Skills Experience with Microsoft Azure and cloud-based application development. Understanding of AI-assisted coding tools such as GitHub Copilot or Tabnine and their impact on software development efficiency. Basic understanding of machine learning libraries and how they interact with Node.js and Python-based services.