The company
Waylet is Repsol’s payments app, well known across Spain, with millions of monthly active users and terabytes of data flowing through it — payment transactions alone exceeded 20 million per month.
My role
My journey through entrepreneurship made it clear that, despite my passion for mobile, my drive to explore new tools and keep growing was pushing me towards backend engineering. Joining Waylet as a freelance Backend Engineer was a masterclass in what large-scale software really looks like.
A project of this size demands very high technical standards: everything has to be scalable, thoroughly tested and bulletproof to serve users reliably around the clock — not just Waylet customers, but also several Repsol business units consuming its APIs.
Responsibilities
- Designing and building backend services with a focus on performance and maintainability.
- Building REST APIs and real-time messaging within an event-driven microservices architecture.
- Thorough testing (unit and integration) following TDD.
- Working closely with frontend, mobile, product and DevOps teams in an agile environment.
What I took away
I learned to think in mid-to-long-term technical strategies: something that works today can become tomorrow’s bottleneck if it doesn’t scale in terms of resources, costs or reliability.
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