Senior iOS Engineer in London

About The Role

At SumUp, we are on a mission to bring merchants and consumers closer together and help local communities thrive. With SumUp Pay, we are building a rewarding banking experience that connects people to the small businesses they love while enabling free transactions for our merchants. SumUp Pay helps consumers manage their money with ease and get more from everyday spending. It offers seamless payment experiences and financial tools designed for modern life—spanning banking, cards, savings, and open banking. This is a high-impact, hands-on engineering role where you will own the development and quality of the SumUp Pay iOS application. You will work directly on the features that consumers interact with every day, collaborating closely with Backend Engineers, Product Managers, Designers, and Android Engineers to deliver polished, reliable, and impactful mobile experiences.

What You’ll Do

• Build and ship features across key consumer banking product areas—including KYC flows, card management, savings, open banking consent, and payment experiences.
• Write clean, testable Swift code and participate actively in code reviews to uphold high engineering standards across the codebase.
• Contribute to and evolve the iOS app architecture, including modularisation, dependency management, and scalability patterns as the product grows.
• Own performance and reliability by monitoring crash rates, proactively identifying issues, and driving app stability before they impact consumers.
• Maintain a culture of quality by writing unit and UI tests and contributing to the health of our CI/CD pipelines.
• Collaborate cross-functionally with Backend Engineers on API design, Product Managers on roadmap priorities, and Designers on seamless user experiences.

What Makes You Great For This Position

• Strong proficiency in Swift and deep knowledge of the iOS framework (Objective-C knowledge is a plus).
• Solid understanding of RESTful API integration and experience working with backend engineers on API design.
• Experience working with agile methodologies, CI/CD pipelines, and pair programming.
• Deep care for user interaction, usability, and interface quality—you build things that feel great to use.
• Ability to understand a large problem, design a solution, break it into deliverable chunks, and ship it independently.
• Passion for clean, maintainable, and testable code and a genuine pride in your craft.
• Mature, business-minded approach—balancing high-quality engineering with pragmatism in a fast-paced environment.
• Self-driven and proactive nature, comfortable owning a domain with limited direct oversight.
• Previous experience in payments, financial services, or fintech environments is a strong plus.

Why you should join SumUp

• Opportunity to work with SumUppers globally on large-scale fintech products used by millions of businesses worldwide.
• 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 SumUp’s future success.
• A dedicated annual L&D budget for your individual development, which can be used to attend conferences and/or advancing your career through further education.
• Competitive Health & Life Insurance: Includes comprehensive cover (optical, dental) and Life Assurance (2 × your salary).
• Financial Future: A corporate pension scheme and a referral bonus for bringing in top talent.
• Generous time off: 28 days of paid leave plus public holidays and special leave days.
• Break4me: 1-month paid sabbatical after 3 years of service.
• Culture of Connection: Attend global offsites and/or hackathons with your teammates.

About SumUp

Be empowered to do more that matters. At SumUp, we are on a mission to empower small businesses across the globe by providing a vast set of simple and affordable business tools to help them start, run, and grow their businesses. Today, over 4 million businesses in 36 markets rely on SumUp 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 SumUppers 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 an inclusivity and continuous learning culture, providing a safe space for personal and professional growth. Our differences make us unique and strong as we strive to create an environment where everyone belongs and feels supported, no matter how they identify. SumUp is proud to be an Equal Employment Opportunity employer, actively seeking and embracing diversity in our workforce. We don’t make hiring or employment decisions based on race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by company policy. Our commitment extends beyond recruitment to creating a safe and respectful workplace where harassment of any form is strictly prohibited.

Job Application Tip

We recognise that candidates feel they need to meet 100% of the job criteria in order to apply for a job. Please note that this is only a guide. If you don’t tick every box, it’s ok too because it means you have room to learn and develop your career at SumUp.