Full Stack JavaScript Engineer

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 platformImplement new AI provider integrations and chat functionalitiesWork with modern React-based frontend and Node.js/Express backend architectureCollaborate on database design and optimization using MongoDBImplement and maintain real-time features using WebSocket connectionsWrite comprehensive tests and ensure code quality through automated testingDeploy and maintain containerized applications using DockerParticipate in code reviews and maintain high development standardsRequired Technical Skills:Frontend Development:React.js (v18+) with modern hooks and functional componentsTypeScript for type-safe

developmentVite for build tooling and development serverTailwindCSS for styling and responsive designRadix UI and Headless UI for accessible component librariesTanstack Query (React Query) for data fetching and state managementReact Router for client-side routingState management with modern React patternsBackend Development:Node.js (v18+) with Express.js frameworkMongoDB with Mongoose ODM for database operationsPostgreSQL structured data storageRedis for caching and session managementRESTful API design and implementationJWT and session-based authenticationDevOps & Infrastructure:Docker and Docker Compose for containerizationMongoDB database administrationEnvironment configuration and secrets managementDevelopment Tools:Git with advanced workflows (rebasing, merging, conflict resolution)ESLint and Prettier for code qualityRequired Experience:3+ years of full-stack JavaScript/TypeScript developmentFluent in English, both written and verbalExcellent communication and collaboration skillsAbility to work independently and manage complex projectsNice to Have:Experience with OpenAI API, Anthropic Claude, or similar LLM APIsUnderstanding of prompt engineering and AI model integrationLangChain framework for AI application developmentRAG (Retrieval-Augmented Generation) implementation experienceWork Arrangement:Availability to work on-site from our Madrid office a few days per week, with the rest of the time remote.

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.We are seeking an experienced Full Stack Developer to join our team working on