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.
WHO WE ARE 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. We also leverage metadata analysis to drive intelligent insights.
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.
ABOUT THE ROLE 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.
CORE RESPONSIBILITIES 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




Work with background job processing, scheduled tasks, and asynchronous workflows
Contribute to AI-driven features, LLM integrations, and prompt engineering
Integrate web applications with data platforms (PowerBI, Databricks, Azure Data Lake Storage)
Ensure scalable, secure, and production-ready implementations
Maintain high test coverage and participate in code reviews
Monitor and debug production systems independently
Collaborate with technical and business stakeholders
REQUIRED TECHNICAL SKILLS Frontend & Web Strong expertise in React + TypeScript
Advanced HTML5 / CSS3 (Bootstrap, Tailwind CSS)
REST API design and consumption
Solid experience with Node.Js + Express.Js
MySQL / MariaDB — schema design, query optimization, connection pooling, migrations
Redis — caching, job queues, distributed locking
Background job processing (BullMQ or similar queue systems)
JWT authentication and role-based access control
Scheduled task management (cron jobs)
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
AI & Prompt Engineering Understanding of AI-driven applications and LLM integrations
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)
Input validation and schema enforcement (Joi or similar)
Awareness of OWASP Top 10, rate limiting, CORS, and secure authentication flows
NICE TO HAVE PowerBI API integration and DAX queries
Azure Static Web Apps or similar deployment platforms
Experience with scalable cloud architecture (Azure preferred)
SOFT SKILLS High ownership mentality — you treat features as yours from start to finish
Professional and structured communication
Strong problem-solving ability
AI-adaptive mindset — comfortable working with rapidly evolving technologies
Team-oriented but capable of independent execution
Production-aware — you think about what happens after deployment
REQUIREMENTS Professional experience of at least 3 years (mandatory)
German — Nice to have
WHY IT'S A GREAT IDEA TO JOIN US Plenty of room to bring your ideas to life
Modern work atmosphere and office equipment
Company events and activities
Open company culture with flat hierarchies
Always the latest hardware
Versátil working hours
Competitive salary based on your experience
Thorough onboarding
Access to coaching programs
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📌 Full Stack Engineer (Valencia)
🏢 Numbero Spain
📍 Valencia