Mid BackEnd Engineer APIs (SaaS)

Our client is looking for a Mid BackEnd Engineer with a strong focus on API development to join their Product Development team. You will contribute to designing and building scalable backend services that power high-impact, data-driven products in the renewable-energy technology space.

If you enjoy solving complex problems, writing clean and reliable code, and working with modern cloud-native architectures, this role will place you right at the core of a mission-driven engineering environment.

Central Barcelona (very well connected).

SaaS platform

Key Responsibilities
Develop, maintain, and document RESTful APIs for both public and internal use.
Write clean, maintainable, and testable code following best engineering practices.
Troubleshoot, debug, and optimise existing APIs and backend services.
Diagnose and solve complex problems across API layers, database queries and cloud environments.
Participate in code reviews and contribute to architectural and performance improvements.
Collaborate with cross-functional teams to design and deliver scalable interfaces.
Stay up to date with the team’s technologies and share knowledge proactively.
Requirements

Mandatory

3–5 years of experience in backend development, with strong focus on APIs.
Solid knowledge of TypeScript and Node.js (experience in other languages is welcome, but TypeScript understanding is essential).
Experience working with cloud environments (AWS preferred, but other cloud providers are also acceptable).
Experience with relational databases (PostgreSQL is a strong plus).
Strong understanding of REST API design and principles.
Experience using Git, pull requests and CI/CD workflows.
Knowledge of clean code principles, design patterns, software architecture, cloud fundamentals and API-first development.
Strong communication skills in English, both written and verbal.

Nice to Have

Experience with Serverless, especially AWS Lambda and API Gateway.
Experience with event-driven systems (Kafka, AWS SQS, RabbitMQ…).
Knowledge of Terraform or Infrastructure as Code.
Familiarity with observability practices and tools: Grafana, CloudWatch, Express logging, etc.
Awareness of database modelling best practices.
Interest in mentoring or sharing knowledge within the team.
What Our Client Offers
The opportunity to work on impactful products that accelerate the adoption of clean and reliable energy.
A collaborative, mission-driven and diverse engineering environment.
Continuous learning in cloud, serverless, APIs, and scalable architecture.
Hybrid work modality (2 days of home office)
Salary range 40K–50K (depending on experience)