Senior Software Engineer (Frontend/Backend)

Are you a React Master who speaks the language of Data?

Do you thrive on building sleek, high-performance interfaces while having the technical "muscle" to orchestrate complex data pipelines in the background? If you are tired of basic apps and want to build systems where every pixel on the screen is backed by massive, real-time data processing, this is the challenge you’ve been looking for.

Our client doesn’t just build software; they build the infrastructure that powers data-driven decisions at scale. We are looking for a Senior Software Engineer (70% Frontend / 30% Data-Driven Backend) to join an elite, high-performance team in the heart of Barcelona.

In this role, you will lead the evolution of sophisticated React-based dashboards, but you won't stop at the UI. You will dive deep into the engine room, using Python to manipulate large datasets, manage event-driven architectures, and ensure that the data flowing into your interfaces is fast, accurate, and scalable.

Main Responsibilities

• Architect the Visual Experience (70%): Take full ownership of the frontend ecosystem using React, TypeScript, and JavaScript. You will build and maintain high-performance UIs that make complex data intuitive and actionable.
• Master the Data Flow (30%): Unlike traditional backend roles, your Python focus will be on data manipulation and engineering. You will build automated reporting systems, manage data pipelines (Airflow/Dagster), and interact with analytical databases like ClickHouse or BigQuery.
• Scale High-Load Systems: Maintain and optimize systems built for massive scale, ensuring reliability through event-driven architectures (Kafka, RabbitMQ, SQS).
• Cloud & Observability: Deploy and monitor your solutions within AWS, setting up robust logging and alerting (Prometheus, Grafana, Sentry) to maintain a "zero-downtime" mindset.

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• Automate Everything: Bridge the gap between complex business workflows and technical execution through smart automation and third-party integrations (REST APIs, Webhooks).

Core Skills/Experience

• The Frontend Expert: You have 5+ years of experience in full-stack environments, but your heart beats for React. You understand state management, performance optimization, and modern styling at an elite level.
• The Data-Savvy Backend Developer: You aren't just "familiar" with Python; you know how to use it to move, transform, and analyze data. You understand how to build systems that don't just store data, but process it.
• Architectural Thinker: You have hands-on experience with AWS and understand the beauty of Event-Driven Architectures.
• Pipeline Proficient: You’ve worked with data processing frameworks (like Airflow) and know your way around analytical databases.

What's on offer

• The opportunity to work with a world-class team of DSP and mobile marketing experts.
• Accelerated career growth and high ownership from day one.
• A collaborative, transparent, and innovation-driven environment.
• A chance to contribute to a product-led company that is defining the future of mobile growth and programmatic media.
• Relocation to Barcelona if needed

Our recruitment process

• Step 1: Initial Interview with on of our Recruiters
• Step 2: Interview with our client's HR Manager
• Step 3: Home-test challenge
• Step 4: Interview with our client's HM
• Step 5: In-depth technical Interview