Full Stack JavaScript Engineer Fullstack

We are seeking an experienced Full Stack Developer to join our team working on an open-source AI chat platform. The successful candidate will contribute to developing and maintaining a sophisticated conversational AI application that integrates multiple AI providers and offers a rich user experience, while collaborating closely with product and design stakeholders.

Key Responsibilities

• Develop and maintain both frontend and backend components of the AI chat platform
• Implement new AI provider integrations and chat functionalities
• Work with modern React-based frontend and Node.js/Express backend architecture
• Collaborate on database design and optimization using MongoDB
• Implement and maintain real-time features using WebSocket connections
• Write comprehensive tests and ensure code quality through automated testing
• Deploy and maintain containerized applications using Docker
• Participate in code reviews and maintain high development standards

Required Technical Skills

• Frontend Development: React.js (v18+), TypeScript, Vite, TailwindCSS, Radix UI, Headless UI, TanStack Query, modern React patterns
• Backend Development: Node.js (v18+), Express.js, RESTful API design, JWT and session-based authentication, MongoDB with Mongoose, PostgreSQL structured data storage, Redis for caching and session management
• DevOps & Infrastructure: Docker, Docker Compose, MongoDB database administration, environment configuration and secrets management, containerized applications
• Development Tools: Git (advanced workflows: rebasing, merging, conflict resolution), ESLint, Prettier
• Testing: Jest, Cypress or Playwright for unit, integration, and end-to-end testing

Work Arrangement

Availability to work on-site from our Madrid office a few days per week, with the rest of the time remote.

Required Experience

• 2+ years of React.js development with modern patterns
• 2+ years of Node.js and Express.js backend development
• 1+ year of MongoDB database experience
• Proven track record with Docker and containerized applications

Soft Skills

• Strong problem-solving and debugging abilities
• Excellent communication and collaboration skills
• Ability to work independently and manage complex projects
• Attention to detail and commitment to code quality
• Adaptability to rapidly evolving AI technologies

Nice to Have

• Experience working closely with Product Managers or in product-driven environments
• Ability to contribute to product decisions, user experience improvements, and feature prioritization
• Understanding of product lifecycle, user needs, and data-driven decision making
• Experience with real-time applications and WebSocket implementation
• Experience with Kubernetes and advanced container orchestration
• Experience with performance monitoring and observability tools
• Familiarity with progressive web app (PWA) development
• npm workspaces for monorepo management

AI & Integration

• Experience with OpenAI API, Anthropic Claude, or similar LLM APIs
• Understanding of prompt engineering and AI model integration
• RAG (Retrieval-Augmented Generation) implementation experience