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    Full Stack JavaScript Engineer

    • Hybrid
      • Madrid, Comunidad de Madrid, Spain
    • Fullstack

    Job description

    Yopeso has been developing a diverse range of software products, from large-scale applications to smaller solutions, for 20 years. With a growing team of over 300 employees across five locations, we are dedicated to fostering a culture of growth, transparency, and professionalism.

    At Yopeso, we value authenticity, curiosity, and ambition. These values drive us to build strong connections within our community and with our partners, ensuring trust, integrity, and transparency in all our business practices. We strive to maintain the highest professional standards and continuously challenge ourselves to develop high-quality, high-performance, and secure software solutions.

    Our approach is rooted in efficient collaboration among passionate professionals working in agile teams. Guided by curiosity and ambition, we strive to create products that are meaningful and impactful, while remaining true to our authentic selves.

    Job requirements

    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+) with modern hooks and functional components

    • TypeScript for type-safe development

    • Vite for build tooling and development server

    • TailwindCSS for styling and responsive design

    • Radix UI and Headless UI for accessible component libraries

    • Tanstack Query (React Query) for data fetching and state management

    • React Router for client-side routing

    • State management with modern React patterns

    Backend Development:

    • Node.js (v18+) with Express.js framework

    • MongoDB with Mongoose ODM for database operations

    • PostgreSQL structured data storage

    • Redis for caching and session management

    • RESTful API design and implementation

    • JWT and session-based authentication

    DevOps & Infrastructure:

    • Docker and Docker Compose for containerization

    • MongoDB database administration

    • Environment configuration and secrets management

    Development Tools:

    • Git with advanced workflows (rebasing, merging, conflict resolution)

    • ESLint and Prettier for code quality


    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:

    • 3+ years of full-stack JavaScript/TypeScript development

    • 2+ years of React.js development with modern patterns

    • 2+ years of Node.js and Express.js backend development

    • 1+ years 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

    • Bun runtime familiarity

    • Jest and Cypress or Playwright for testing (unit, integration, e2e)

    AI & Integration:

    • Experience with OpenAI API, Anthropic Claude, or similar LLM APIs

    • Understanding of prompt engineering and AI model integration

    • LangChain framework for AI application development

    • RAG (Retrieval-Augmented Generation) implementation experience

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