Full Stack Developer - Part Time

NUMBERO, a leading German tech startup revolutionizing after-sales processes in car dealerships, is looking for a Full Stack Engineer (m/f/d) to join our growing development hub in Valencia.At NUMBERO, our mission is to equip car dealerships with cutting-edge tools to optimize their after-sales operations.We integrate trusted sources for parts and labor costs, various Dealer Management Systems, and other relevant data sources.Headquartered in Germany and supported by a growing international team, we focus on innovation, collaboration, and delivering outstanding value to our clients.Our Valencia office plays a key role in shaping the future of our technologies and services.We are looking for a versatile Full Stack Engineer with strong backend and data engineering skills.You will work across a Node.Js backend, React and TypeScript frontend, and data platforms such as Databricks, supporting data pipelines, integrations, analytics, and AI-driven features.The role requires end-to-end ownership, from database and API design through frontend delivery, deployment, and monitoring.You should be comfortable working across application development, data workflows, job queues, migrations, authentication, and production systems.Develop and maintain web application features across the full stack (React + TypeScript frontend, Express.Js + TypeScript backend)- Design and implement database schemas, migrations, and optimized queries (MySQL / MariaDB)- Build and maintain REST APIs and integrate them with frontend systems- Integrate web applications with data platforms (PowerBI, Databricks, Azure Data Lake Storage)- Maintain high test coverage and participate in code reviews- Frontend & Web- Strong expertise in React + TypeScript- Advanced HTML5 / CSS3 (Bootstrap, Tailwind CSS)- Git version control Backend & Infrastructure- Solid experience with Node.Js + Express.Js- MySQL / MariaDB - schema design, query optimization, connection pooling, migrations- Redis - caching, job queues, distributed locking- Docker - containerization, multi-stage builds, Docker Compose- JWT authentication and role-based access control- Data & Cloud- Practical experience with Databricks and Azure Data Lake Storage (ADLS)- Understanding of data pipelines and structured/unstructured data handling- Experience integrating web applications with data platforms (PowerBI, Databricks, ADLS)- Familiarity with Azure services (Azure AD, Static Web Apps, or similar)- Understanding of data synchronization pipelines and ETL processes Ability to design, test, and refine prompts for reliable AI outputs- Experience working with AI APIs (OpenAI, Azure AI, Anthropic, etc.)Code Quality & Security- Writing and maintaining unit tests (Jest, Supertest)- Maintaining high test coverage standards (95%+ preferred)- E2E testing frameworks (Cypress, Playwright)- Prometheus / Grafana monitoring- Azure Static Web Apps or similar deployment platforms- CI/CD pipeline configuration- Experience with scalable cloud architecture (Azure preferred)- UI/UX design awareness Production-aware - you think about what happens after deployment English - Fluent (mandatory)- Spanish - Fluent (mandatory)- German - Nice to have WHY IT’S A GREAT IDEA TO JOIN US- Modern work atmosphere and office equipment- Flexible working hours- Permanent full-time position- de with the subject line “Full Stack Engineer”.

We are looking for a versatile Full Stack Engineer with strong backend and data engineering skills., The role requires end-to-end ownership, from database and API design through frontend delivery, deployment, and monitoring. You should be comfortable working across application development, data workflows, job queues, migrations, authentication, and production systems. Develop and maintain web application features across the full stack (React + TypeScript frontend, Express.Js + TypeScript backend)

• Design and implement database schemas, migrations, and optimized queries (MySQL / MariaDB)
• Build and maintain REST APIs and integrate them with frontend systems
• Integrate web applications with data platforms (PowerBI, Databricks, Azure Data Lake Storage)
• Maintain high test coverage and participate in code reviews
• Frontend & Web
• Strong expertise in React + TypeScript
• Advanced HTML5 / CSS3 (Bootstrap, Tailwind CSS)
• Git version control Backend & Infrastructure
• Solid experience with Node.Js + Express.Js
• MySQL / MariaDB - schema design, query optimization, connection pooling, migrations
• Redis - caching, job queues, distributed locking
• Docker - containerization, multi-stage builds, Docker Compose
• JWT authentication and role-based access control
• Data & Cloud
• Practical experience with Databricks and Azure Data Lake Storage (ADLS)
• Understanding of data pipelines and structured/unstructured data handling
• Experience integrating web applications with data platforms (PowerBI, Databricks, ADLS)
• Familiarity with Azure services (Azure AD, Static Web Apps, or similar)
• Understanding of data synchronization pipelines and ETL processes Ability to design, test, and refine prompts for reliable AI outputs
• Experience working with AI APIs (OpenAI, Azure AI, Anthropic, etc.)Code Quality & Security
• Writing and maintaining unit tests (Jest, Supertest)
• Maintaining high test coverage standards (95%+ preferred)
• E2E testing frameworks (Cypress, Playwright)
• Prometheus / Grafana monitoring
• Azure Static Web Apps or similar deployment platforms
• CI/CD pipeline configuration
• Experience with scalable cloud architecture (Azure preferred)
• UI/UX design awareness Production-aware - you think about what happens after deployment English - Fluent (mandatory)
• Spanish - Fluent (mandatory)

NUMBERO, a leading German tech startup revolutionizing after-sales processes in car dealerships, is looking for a Full Stack Engineer (m/f/d) to join our growing development hub in Valencia. At NUMBERO, our mission is to equip car dealerships with cutting-edge tools to optimize their after-sales operations. We integrate trusted sources for parts and labor costs, various Dealer Management Systems, and other relevant data sources. Headquartered in Germany and supported by a growing international team, we focus on innovation, collaboration, and delivering outstanding value to our clients.