Senior Backend Engineer

About the team

At Sum Up, we're on a mission to bring merchants and consumers closer together and help local communities thrive. Within the Consumer Mission, we're building a rewarding banking experience that connects people to the small businesses they love while tackling some of the most technically demanding challenges in fintech: critical infrastructure migrations, smooth, uninterrupted payment experiences, seamless open banking integrations, and high‑availability banking systems that can’t afford to fail – all while enabling free transactions for our merchants.

This role sits at the heart of that work — you’ll take real ownership of backend services that are close to our consumers, directly shaping their everyday experience, with impact that’s visible and felt across the entire platform.

What you'll do Build and maintain Backend services for Core neobanking features including bank transfers, open banking, savings accounts, and payment processing

Take end-to-end ownership of features and projects, covering scoping, design, development, testing, deployment, and maintenance, leveraging Go along with Docker and Kubernetes for container orchestration.

Take ownership of critical infrastructure migrations — including our banking core system transitions — without disrupting live customer experiences

Collaborate closely with cross-functional teams including product, design, data science, security, and operations) to understand requirements, provide technical insights, and contribute to architecture discussions that ship meaningful banking features end-to-end Support fellow developers and actively help build a collaborative, innovative engineering culture

Shape technical architecture and lead code reviews, helping define and promote best practices in code quality, testing, automation, and security to raise the overall engineering bar.

Build and integrate tools and systems that improve operational efficiency and reliability, with strong observability through monitoring, alerting, and hands‑on involvement in incident response and post‑mortems.

You'll be great for this role if you have…Strong proficiency in Go, Kotlin or Python, with a track record of building scalable, production-grade backend services

Experience working with cloud platforms (AWS or comparable) and container orchestration tools such as Docker and Kubernetes Solid understanding of SQL and No

SQL databases, distributed systems, and the trade-offs that come with high-availability requirements

Comfort navigating complex, regulated environments — whether that's financial services, payments, or similarly high-stakes domainsA collaborative, product-oriented mindset with the ability to work independently, communicate clearly, and adapt when priorities shift

Any of the following would be considered a plus Previous experience in a Growth-focused engineering team.

Familiarity with the Fintech or Banking regulatory landscape.

No visa sponsorship available with this position

Why you should join Sum Upð Opportunity to work with a truly global, multicultural team from our central London Bridge location. This involves an office-first setupð Commitment to Diversity and Inclusion: be part of a workplace that values and promotes diversity, fostering an inclusive environment where everyone's perspectives are respected and embracedð Enrolment onto our Virtual Stock Option programme: you will own a stake in Sum Up's future successð Generous time off: enjoy 28 days of paid leave, plus bank holidays and special leavesð A dedicated annual L&D budget for attending conferences and/or advancing your career through further educationð Health matters: private health insurance, including optical and dentalð Life made easier: salary-sacrifice commuter benefits via Gogetað¼ Financial security: retirement scheme (Sum Up matches 7% when you contribute 5%)ð¡ Peace of mind: life insurance from Met Life for 2 your salaryð Break4me: 1-month sabbatical after 3 years of serviceð Referral Bonus: earn additional rewards by referring talented individuals to join the Sum Up team About Sum Up Be  empowered to do more that matters.

At Sum Up, we're on a mission to empower small businesses…