Staff Software Engineer - Payment Processing

Location: London Workplace: OnSite Company Description We’re http://checkout.comCheckout.com http://Checkout.com. You might not know our name, but companies like eBay, Spotify, Klarna, Uber, and Sony do, because we’re behind many of the digital experiences you use every day. We are where the world checks out, enabling over 10 billion transactions yearly for more than one billion global shoppers. Whether you want to book a holiday, order food, renew a subscription, or check out online, there’s a good chance our tech powers the payments behind the scenes. Our platform helps the most ambitious businesses deliver effortless digital experiences, at scale. If you want to do career-defining work, you’ve come to the right place. We move fast, think globally, and believe great teams are built by hiring exceptional people with conviction, curiosity, and the desire to make an impact. With 20 offices across six continents and London as our HQ, we’re shaping the future of fintech – and we’re just getting started. As a Staff Engineer (Payment Processing) at Checkout.com http://Checkout.com, you will set the technical direction for our Gateway, Routing and Payout platforms. Every payment and payout we process passes through these systems, from the merchant's API request to the routing decision that sends it to the right acquirer, payment method or payout rail. Correctness matters on every transaction, and small changes in availability, latency or routing quality show up directly in our merchants' approval rates and revenue. This is a role for engineers who are energised by scale and by the hard trade-offs that come with it: latency budgets on the authorisation path, failure domains and blast radius, consistency and idempotency across regions, and the operational reality of running critical infrastructure around the clock. You will operate as a force multiplier across multiple teams - shaping architecture, raising the engineering bar, and turning ambiguous, business-critical problems into designs that can be delivered incrementally. We're looking for individuals with deep technical judgement, strong ownership, and a pragmatic approach to breaking big problems into smaller iterations that deliver value continuously. How you'll make an impact - Own the architecture of high-throughput, low-latency distributed systems, defining the service boundaries, data models and integration patterns that let them scale by an order of magnitude - Design for resilience from first principles - redundancy, graceful degradation, backpressure, idempotency and recovery - so that partial failures never become customer-facing outages - Set and defend the non-functional requirements that matter: availability targets, latency percentiles, throughput ceilings, data durability and recovery objectives - Lead the hardest technical decisions end to end, from problem framing and design review through to production rollout, migration and decommissioning of what came before - Drive operational excellence by improving observability, alerting, capacity planning, load and chaos testing, and incident response, and by closing the loop on the root causes you find - Raise the engineering bar across teams through design reviews, code review, pairing and mentorship, growing the senior engineers around you - Partner with product, platform and other engineering teams to sequence delivery, remove blockers and keep multi-team programmes aligned on a single technical direction - Make pragmatic build-versus-buy and refactor-versus-rewrite calls, and communicate the reasoning and trade-offs clearly to both engineers and senior leadership Experience and qualifications - Significant experience building and operating distributed backend systems in production, with a track record of technical leadership across multiple teams - Demonstrable experience designing for high throughput and low latency, and a strong intuition for where systems break under load - Deep understanding of resilience patterns in distributed systems: idempotency, retries and backoff, circuit breaking, queueing and backpressure, consistency and failure modes - Strong proficiency in either .NET or Java, and the ability to write clear, production-ready code that others can maintain - Experience with event-driven and streaming architectures, and with relational and non-relational data stores at scale - Hands-on experience with cloud-based application development (we use AWS & Azure), containers, orchestration and infrastructure as code - Experience owning production systems on call, with a strong sense of ownership for observability, monitoring and incident response - Experience leading complex migrations or re-architectures of live, business-critical systems with no loss of availability or data integrity - Excellent communication skills, able to influence without authority, write clear design documents, and express technical trade-offs to engineering and non-technical audiences alike Nice-to-haves - Experience in payments, financial services or another domain with strict correctness, auditability or regulatory requirements - Experience with multi-region or active-active architectures, including data replication and failover strategies - A history of mentoring engineers into senior and staff-level roles Additional Information 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. Life at Checkout.com http://Checkout.com We understand that work is just one part of your life. Our hybrid working model offers flexibility, with three days per week in the office to support collaboration and connection. Curious about what it’s like to be part of our team? Visit our Careers Page https://www.checkout.com/careers to learn more about our culture, open roles, and what drives us. For a closer look at daily life at Checkout.com http://Checkout.com, follow us on LinkedIn https://www.linkedin.com/company/checkout/life/ and Instagram https://www.instagram.com/checkout_com/