Join the fintech revolution with Mambu, the leading SaaS cloud banking platform. We're on a mission to make banking better for a billion people. We're engineering the future of financial services with AI at its core. At Mambu, AI isn't a feature — it's how we're rebuilding banking from the ground up. If you're ready to apply cutting-edge technology to problems that affect millions of people, your next chapter starts here. Learn more here .
We are hiring Senior Backend Software Engineers across all teams. As a Senior Backend Software Engineer, you will be responsible for:
~ Developing bank connectivity and payment automation products, features, and capabilities, with a focus on security, stability, and performance
~ Owning architectural decisions for complex, high-impact projects and driving technical direction across teams
~ Collaborating with Product Managers and DevOps Software Engineers to maintain a fast-paced, iterative, and continuously improved product development and delivery process
~ Applying security by design principles to public and internal APIs
~ Solving architectural and technical challenges to reduce complexity while creating value for customers and users
~ Mentoring and upskilling junior and mid-level engineers through code reviews, pair programming, and technical guidance
~ Defining and executing Numeral's technical roadmap to improve team velocity and control technical debt




~ Acting as a technical reference and escalation point for critical incidents and high-stakes production issues.
~5+ years of professional software engineering experience, with significant hands‑on experience in Golang
~ Background in fintech, banking, or payments (SEPA, Swift, Ebics…), with an understanding of the regulatory and operational constraints of the industry
~ Proven track record designing and owning complex, distributed backend systems in production
~ Deep experience with relational databases and SQL, including high-concurrency environments, transaction management, and isolation levels at scale
~ Strong understanding of the challenges of running a high-volume SaaS platform at scale, with a track record of producing quality, maintainable, well-documented code that respects best practices
~ Advanced API design skills, with a strong focus on security, versioning, and documentation
~ Demonstrated ability to mentor engineers and elevate team-wide engineering standards
~ You are curious, interested in business understanding and product oriented
~ You are highly autonomous, proactive, and comfortable driving ambiguous technical problems to resolution

Nice-to-have skills
DevOps appetite - you have been in involved in implementing / using CI using Gitlab and Kubernetes
Cloud hosting with AWS and experience with EC2, S3, EKS, RDS…
Familiar with Kafka or similar message broker middlewares
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📌 Senior Software Engineer - C# - (Hybrid Remote) (Barcelona)
🏢 Mambu Payments (formerly Numeral)
📍 Barcelona