Full-Stack Developer (AI Focus)

About the Role

Join our Development team as a Full-Stack Developer and play a key role in building and scaling our platforms and products. You will work across our entire AI technology stack to deliver a seamless and powerful user experience, contributing to projects with a fast-shipping approach and a modern tech stack.

Key Responsibilities

• Design, implement, and maintain RESTful APIs with NextJS/Express for user authentication, data processing, and analysis workflows.
• Build AI agents using Model Context Protocol (MCP) with Claude SDK to access real-time data, APIs, and tools, enabling agents to take actions and combine LLM reasoning with real-world integration.
• Develop AI agents with LangGraph + LangFuse to handle multi-step reasoning, agent collaboration, task handoffs, conversation state management, and complex decision trees.
• Develop and maintain features on both our React frontend and Node.js (NextJS) backend.
• Build intuitive user interfaces using TypeScript, Vite, React, and our UI component library for media uploads, analysis management, and product interaction.
• Integrate our platform with external services (e.g., Payment Service Providers, APIs) and handle incoming webhooks for asynchronous tasks.
• Collaborate closely with AI product managers and specialists to translate complex requirements into robust features using AI design prompts.
• Contribute to database schema design and write migrations for PostgreSQL & BigQuery databases.
• Collaborate on application deployment and assist in maintaining our cloud infrastructure on Google Cloud Platform (GCP).

What You Bring

• Extensive knowledge of Javascript/Typescript.
• Extensive experience with the Python framework.
• Deep API Integration experience with 3rd party vendors and various SDKs.
• TypeScript Proficiency in both frontend (React) and backend (Node.js) environments.
• Frontend Expertise: Strong experience with React, modern state management (Hooks, Context API).
• Backend Expertise: Solid experience building and consuming REST APIs with Node.js, NextJS, or Express.
• Database Skills: Experience with PostgreSQL and working with an ORM or query builder.
• Knowledge of LangGraph, LangChain, LangFuse.
• Problem-Solving Mindset: Collaborative and eager to tackle new challenges in a fast-paced environment.
• Passion for AI: Genuine passion for artificial intelligence and a desire to build products leveraging its capabilities.
• Very High Agency: Ability to work with autonomy and freedom to implement business vision in consultation with Product Owner and Engineering Manager.
• Creativity and Proactivity: Passion for building great products, proposing new features, and improving user experience.

Nice to Have

• AI Project Experience (ML, LLMs).
• Familiarity with UI component libraries.
• Knowledge of cloud platforms like Google Cloud Platform (GCP).

Why You’ll Love Working With Us

• High-Impact Role: Key player in a small, agile team building a greenfield project.
• Modern Technology: Work with a cutting-edge tech stack and best practices.
• Growth & Learning: Gain deep experience in AI-driven applications, cloud-native architecture, and real-time systems.
• Stability & Vision: Startup energy backed by a large, successful company.
• Collaborative Culture: Open communication, teamwork, and passion for building exceptional products.
• Growth and Career Development: Flexible career path, personalized internal training, and an annual budget for external learning.
• Work-Life Balance: Flexible schedule, flextime, option for full remote or office work, free Friday afternoons, and a 35-hour workweek in July/August.
• Comprehensive Benefits: Competitive salary, full-time permanent contract, top-tier private health insurance (including dental and psychological services), 25 days of vacation plus your birthday off, and flexible vacation options.
• Unique Perks (Office): Free coffee, fresh fruit, snacks, game room, rooftop terrace, ticket restaurant, and nursery vouchers.

Location

• Flexible: Fully remote, hybrid, or in-office at our Barcelona office.