Senior iOS Engineer

Location: London, United Kingdom Team: Consumer

The Consumer team builds and maintains Sum Up Pay — a regulated consumer banking app spanning payments, card management, savings, and open banking, used by hundreds of thousands of customers every day. We're a cross-functional squad of engineers, product managers, and designers working at pace on a product that genuinely matters to the people who rely on it. Right now, we're growing our iOS function to match the ambition of our product roadmap — and this role sits at the heart of that.

As an iOS Engineer, you'll own meaningful parts of the Sum Up Pay experience end-to-end, from onboarding and KYC flows through to savings features and in-app messaging. With a lean iOS team and a growing product surface, there's real scope to shape how we build — not just what we build.

Design, build, and ship iOS features across Sum Up Pay — including KYC and card activation flows, savings, open banking consent, and payment experiences

Take ownership of performance monitoring, crash reporting, and app stability, proactively resolving issues before they reach customers

Contribute to the evolution of our iOS architecture — including modularisation, dependency management, and scalability as the product grows

Partner with the CRM Manager to implement in-app messaging (modals and banners) via Iterable, ensuring correct event instrumentation and display logic on iOS

Write clean, testable Swift code and contribute actively to code reviews, CI/CD pipeline health, and a culture of quality across the team

Strong proficiency in Swift and the iOS framework, with a track record of shipping consumer-facing features in a product environment.

Experience integrating RESTful APIs and collaborating closely with backend engineers on API design and contracts.

Solid understanding of iOS architecture patterns, modularisation, and writing maintainable, well-tested code.

Comfort working in a regulated or fintech environment, with an appreciation for the security, compliance, and data privacy considerations that come with it.

A product-oriented mindset — someone who thinks about the user journey, not just the implementation, and brings both craft and pragmatism to technical decisions.

Opportunity to work with a truly global, multicultural team from our central Covent Garden location, wrapped in historic charm and modern flair. This involves an office-first setup.

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 embraced.

Enrolment onto our Virtual Stock Option programme: you will own a stake in Sum Up's future success.

Generous time off: enjoy 28 days of paid leave, plus bank holidays and special leaves.

A dedicated annual L&D budget for attending conferences and/or advancing your career through further education.

Health matters: private health insurance, including optical and dental.

Life made easier: salary-sacrifice commuter benefits via Gogeta.

Financial security: retirement scheme (Sum Up matches 7% when you contribute 5%).

Peace of mind: life insurance from Met Life for 2× your salary.

Break4me: 1-month sabbatical after 3 years of service.

Referral Bonus: earn additional rewards by referring talented individuals to join the Sum Up team.

Be empowered to do more that matters.

At Sum Up, we're on a mission to empower small businesses across the globe by providing simple and affordable tools that allow them to thrive. Today, over 4 million businesses in 37 markets rely on Sum Up as their financial partner to manage payments, finance and customer relationships.

Our commitment to small businesses is reflected in our diverse team of over 3,000 Sum Uppers from over 90 nationalities, united by global collaboration and an innovative mindset. Our core values lay the foundation for who we are and what we stand for, shaping our work culture and driving our success. We foster inclusivity and a continuous learning culture, providing a safe space for personal and professional growth.

Our differences make us…