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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Software Engineer - **Company:** Dtone - **Location:** Barcelona, Spain - **Salary:** €70,000.0 - €90,000.0 - **Contract:** Permanent contract - **Skills:** Java (Programming Language), Artificial Intelligence, Amazon Web Services, Continuous Integration, Software Debugging, Programming Tools, Distributed Systems, Perl (Programming Language), Hibernate (Java), Java Persistence API, Python (Programming Language), Liquibase, MariaDB, OAuth, OpenID, Swagger, SQL Databases, Openapi, Cloud Platform System, Spring-boot, Backend, Kotlin, Containerization, Git Flow, Kubernetes, Api Design, Restful APIs, Api Management, Docker, Golang - **Published:** July 20, 2026 - **Apply:** https://www.adzuna.es/contact-us.html ## About the Role + Strong experience with Spring Boot and backend API development + Solid Java and/or Kotlin backend development skills + Familiarity with REST APIs, SQL databases, and distributed systems fundamentals + Familiarity with asynchronous processing and event-driven integration patterns + Comfortable with debugging, writing tests, and working in CI/CD + Git workflows + Ability to work effectively in existing/legacy codebases while delivering new features safely + Familiarity with AWS. + Comfortable using AI based development tools, as and when appropriate Nice to have + Knowledge of telecommunications protocols (Gx/Gy/DIAMETER, SMPP) + OAuth2/OIDC and token-based authentication flows + API-first development with OpenAPI/Swagger (including codegen workflows) + MariaDB, JPA/Hibernate, and Liquibase migrations + Exposure to containerized deployments and cloud environments (Docker/Jib, Kubernetes basics) + Knowledge of GoLang, Python and Perl. + Knowledge of GCP. ## Description DT One is looking to onboard a Senior Software Engineer who is passionate about the FinTech industry, and wants to work in a disruptive, fast-growing and exciting environment. A career with DT One provides invaluable experience in an exciting and rapidly expanding market and an opportunity to be part of a truly global company with a workforce of over 50 nationalities. A Senior Software Engineer at DT One is a proficient perfectionist, a focal point within their team, a source of knowledge, and a mentor. This role allows the candidate to work on various technical problems in different stacks, with much room and support for learning and development. You will work in the team that supports our eSim product offering. eSims are a key product offering from DTOne. You will work closely with the teams that support DTOne's core platform and services. We rely on our engineers to architect and deliver the best possible solution to support the business and ensure the best customer experience. We can offer you an environment based on learning, transparency, honesty, and feedback. You will be challenged to own your code (write, test, and deploy). Deployments happen multiple times per day. Our technology is used 24/7 around the world, so it needs to be reliable, secure, and scalable (millions of transactions per day). You will also need to interface with technology teams in different countries. Our environment and packages match the ambition of the company: building world-class engineering teams. What you'll do + Design, develop, and maintain Spring Boot services in Java/Kotlin + Build and support API integrations across internal and external telecom systems + Work with asynchronous/event-driven flows and related messaging patterns + Improve reliability, performance, and observability of existing backend services + Collaborate with product and engineering teams to ship production-ready features Core requirements ## Related Videos - [Docker Compose: Rediscovered](https://www.wearedevelopers.com/videos/1978-docker-compose-rediscovered) - [Go with the Flow: Stop the Leaks Before Your Memory's a Waterfall!](https://www.wearedevelopers.com/videos/100073-go-with-the-flow-stop-the-leaks-before-your-memory-s-a-waterfall) - [Keeping applications secure by evolving OAuth 2.0 and OpenID Connect](https://www.wearedevelopers.com/videos/100152-keeping-applications-secure-by-evolving-oauth-2-0-and-openid-connect) - [Coffee with Developers](https://www.wearedevelopers.com/videos/354-coffee-with-developers) - [Docker build without Docker](https://www.wearedevelopers.com/videos/100114-docker-build-without-docker) - [Retooling and refactoring - an investment in people.](https://www.wearedevelopers.com/videos/371-retooling-and-refactoring-an-investment-in-people) ## Related Articles - [Dev Digest 120 - Apple and peers](https://www.wearedevelopers.com/magazine/455-dev-digest-120-apple-and-peers) - [The Best X (Twitter) Accounts for Developers](https://www.wearedevelopers.com/magazine/294-the-best-x-twitter-accounts-for-developers) - [Dev Digest 121 - AI goes offline](https://www.wearedevelopers.com/magazine/456-dev-digest-121-ai-goes-offline) - [20 Essential Tools For Backend Development](https://www.wearedevelopers.com/magazine/218-20-essential-tools-for-backend-development) - [Is Software Engineering Over-Saturated?](https://www.wearedevelopers.com/magazine/418-is-software-engineering-over-saturated) - [Find a Developer Job: 12 Best Job Sites For Developers](https://www.wearedevelopers.com/magazine/165-find-a-developer-job-12-best-job-sites-for-developers)