Senior Software Engineer I London

Checkout Ltd; City of Westminster; On-site; GBP 60,000 - 80,000; Full time

Job summary

A leading fintech company in the UK is seeking a Senior Software Engineer to enhance their team. This role involves leading projects, designing scalable systems, and collaborating with diverse teams. Candidates should have expertise in programming languages like .NET C#, Java, Go, or Python, along with strong communication skills and the ability to work in agile environments. Ideal for those passionate about technology and looking to make an impact in digital payments.

Qualifications

• Strong understanding of software development principles in backend or full stack.

Responsibilities

• Collaborate with cross‑functional teams including product management.
• Define and design scalable systems in a microservices architecture.
• Write clean, maintainable, and testable code.

Skills

Proficiency in .NET C#

Proficiency in Java

Proficiency in Go

Proficiency in Python

Great communication skills

Experience working in agile environments

Excellent problem-solving skills

Education

Bachelor's or Master's degree in Computer Science, Engineering, or related field

Job description

About Checkout

is one of the most exciting fintechs in the world. Our mission is to enable businesses and their communities to thrive in the digital economy. We're the strategic payments partner for some of the best known fast-moving brands globally such as Wise, The Hut Group, Sony Electronics, Sainsbury's, Deliveroo, Adidas, Klarna and many others. Purpose-built with performance and scalability in mind, our flexible cloud-based payments platform helps global enterprises launch new products and create experiences customers love. And it's not just what we build that makes us different. It's how. Global payments are complex and ever-evolving. At Checkout our software engineers develop the next-generation payments technologies that enable our Merchants to boost their acceptance rates, cut processing costs, fight fraud, and create cutting edge technology that enables extraordinary customer experiences.

We're - you might not know our name, but companies like eBay, ASOS, Klarna, Uber Eats, and Sony do. That moment when you check out online? We make it happen.

is where the world checks out. Our global network powers billions of transactions every year, making money move without making a fuss. We spent years perfecting a service most people will never notice. Because when digital payments just work, businesses grow, customers stay, and no one stops to think about why. With 19 offices spanning six continents, we feel at home everywhere - but London is our HQ. Wherever our people work their magic, they're fast-moving, performance-obsessed, and driven by being better every day. Ideal. Because a role here isn't just another job; it’s a career‑defining opportunity to build the future of fintech.

Role Summary

We're looking for Senior Software engineers who bring fresh ideas, have a curious nature and are passionate about working in an Engineering environment which focuses on building products to achieve the company's strategic goals. You'll get to work with teams from across 's portfolio of products and services who all have a real customer first philosophy. As a Senior Software engineer, you will lead and drive specific projects critical to Checkout's needs with opportunities to switch teams and projects as you and our fast-paced business grow and evolve. We need our engineers to be versatile, display exceptional leadership qualities and be enthusiastic to take on new problems across the full-stack as we continue to push technology forward. With your technical expertise you will lead project priorities, deadlines, and deliverables. You will design, develop, test, deploy, maintain, and enhance software solutions.

Qualifications

• Bachelor's or Master's degree in Computer Science, Engineering, or related field
• Proficiency in .NET C#, Java, Go, or Python, with a strong understanding of software development principles in either a backend or full stack environment
• Great communication skills and ability to interact effectively with a wide range of stakeholders
• Experience working in agile environments and delivering high-quality code within tight deadlines
• Excellent problem-solving skills and the ability to work independently as well as part of a team
• Payments or financial knowledge is a plus, but not a necessity

Responsibilities

• Be part of, and collaborate with, cross‑functional teams including product management, across a large engineering community.
• Define and design loosely coupled, scalable systems in a wider microservices using industry best practices.
• Stay up‑to‑date, use, and spread knowledge of the latest technologies used by Checkout.
• Write clean, maintainable, extendable and testable code on some of Checkout's most impactful systems.
• Build, own and operate your systems to the highest levels of resilience and service.
• Mentor junior team members and assist in their technical development.

Join Us

Join Us Today! If you're passionate about technology, innovation, and making a real impact in the world of digital payments, we want to hear from you. Join our engineering department at and be part of a team that's shaping the future of payments for generations to come. Apply now and let's embark on this exciting journey together! Bring all of you to work. We create the conditions for high performers to thrive - through real ownership, fewer blockers, and work that makes a difference from day one. Here, you'll move fast, take on meaningful challenges, and be recognized for the impact you deliver. It's a place where ambition gets met with opportunity - and where your growth is in your hands. We work as one team, and we back each other to succeed. So whatever your background or identity, if you're ready to grow and make a difference, you'll be right at home here. It's important we set you up for success and make our process as accessible as possible. So let us know in your application, or tell your recruiter directly, if you need anything to make your experience or working environment more comfortable.