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.

¿Tiene su CV preparado? Si es así y confía en que este es el puesto adecuado para usted, asegúrese de enviar su solicitud lo antes posible.

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

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

Background job processing (BullMQ or similar queue systems)

Docker — containerization, multi-stage builds, Docker Compose

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)





Maintaining high test coverage standards (95%+ preferred)

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

E2E testing frameworks (Cypress, Playwright)

PDF generation pipelines (pdf-lib, Puppeteer)

Email automation systems (Nodemailer, templated dispatch)

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

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)

English — Fluent (mandatory)

Spanish — Fluent (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

Flexible working hours

Competitive salary based on your experience

Supportive team spirit

Thorough onboarding

Permanent full-time position

Access to coaching programs

Career development opportunities

HOW TO APPLY

Still reading? Great! Ready to become part of our mission? As we are looking for someone with a good drive, our hard skill requirements are not too strict. What really matters to us is that you bring your own drive and are eager to make a difference. xsgfvud

Send your CV to with the subject line "Full Stack Engineer". We look forward to meet you!

📌 Full Stack Engineer (Valencia)
🏢 Numbero Spain
📍 Valencia