Senior Backend Engineer – Kotlin/Java | FinTech | Spain | Fully Remote via EOR

Are you a Backend Engineer looking to work on the modernisation of a growing FinTech platform?

We're partnering with a growing

lending FinTech

building customer-facing financial products at scale. As the platform continues to evolve, they're looking for a

Senior Backend Engineer

to join the team and help build the next generation of their backend services.

Kotlin

is becoming an increasingly important part of the engineering stack, but you don't need to already be a Kotlin expert. They're equally interested in strong

Java engineers

who understand the JVM ecosystem and are keen to move into Kotlin.

This is a hands-on product engineering role where you'll have the opportunity to build new services, contribute to technical decisions and help modernise an existing technology estate.

Being a growing FinTech means engineers have genuine ownership. They're looking for someone who enjoys solving problems, working closely with Product and taking responsibility for what they build rather than simply picking up tickets.

What you'll be doing Designing and building

scalable backend services

across a modern financial technology platform. Developing new services primarily using

Kotlin . Working across a

cloud-based environment

and helping build reliable, maintainable systems. Designing and developing

APIs, services and backend architecture . Contributing to the ongoing

modernisation of the platform , including moving functionality from legacy technologies into modern JVM-based services. Working with existing services, including parts of the platform written in

PHP . Taking ownership of your work from design through to delivery. Contributing to

technical decisions, code reviews and engineering best practices . Using and engaging with





AI tooling

as part of modern software engineering workflows. Working closely with Software Engineering, Product and other stakeholders in a small, cross-functional team.

What we're looking for At least

5 years of commercial software engineering experience , with a strong focus on backend development. Strong commercial experience with

Kotlin and/or Java . If you're primarily a Java engineer, you should be

open to working with and developing in Kotlin . Previous experience within financial services, ideally FinTech, lending, banking, payments or another regulated financial environment. Strong experience working with

cloud-based systems . Strong understanding of

APIs, services and backend architecture . Experience using or working with

AI tools within software engineering . Strong coding standards with a focus on building

clean, reliable and maintainable software . Comfortable working independently within a

remote product engineering team . Must be

based in Spain with the right to work in Spain .

Nice to have Previous experience with

PHP

or a good understanding of the language. Experience working on

legacy modernisation or technology transformation projects . Experience migrating or rebuilding systems from legacy technologies into

Java, Kotlin or modern JVM architectures . Experience within a

startup, scale-up or smaller product-led engineering environment . Experience specifically within

lending or consumer finance .

Spain – Fully Remote Full-time employment via Employer of Record (EOR)

If you're a Backend Engineer with a strong Java/Kotlin background who wants to work on a modern FinTech platform, contribute to a wider modernisation journey and have genuine ownership over what you build, I'd be keen to speak.

Feel free to apply or message me directly for a confidential conversation.

📌 Back End Developer (Madrid)
🏢 Intro
📍 Madrid