Senior Developer

Senior DeveloperLondon | £70,000 - £90,000 + Benefits Most developers focus on building the features, this role is for someone who thrives on owning what happens once its live.We're working with a well-established SaaS business whose platform is used by thousands of customers globally. Over the past few years, they've grown steadily, expanded their engineering function, and built a reputation for creating reliable products rather than chasing hype.As their platform continues to scale, they're looking for a Senior Developer who enjoys solving complex technical problems, improving systems, and building software that stands up in production.A Typical Day in the Role:Building and improving APIs that support critical platform functionalityInvestigating production issues and tracing problems across distributed systemsWorking with product and engineering teams to design scalable solutionsImproving reliability, observability and performance across existing servicesReviewing code, sharing knowledge and helping raise engineering standards across the teamTackling real-world challenges around third-party integrations, data consistency and system resilienceDebugging complex issues, from flaky dependencies to partial failures, ensuring system reliabilityThe kind of person who'll enjoy this roleYou'll have spent several years building and supporting production systems and understand that software engineering isn't just about writing new code, you’ll value practical engineering, thoughtful decision-making and will be able to balance technical excellence with delivery.You will have:Designed and maintained APIs used by customers or internal teams4-6 years experience, with at least 3+ years at one company, ideally SaaS/platform/scaleup.Supported systems in production and dealt with incidents when things didn't go to planWorked with cloud-native applications or managed infrastructure environmentsIntegrated with external platforms and navigated the challenges that come with themFixed bugs you didn't create and improved codebases you didn't originally writeLearned how to balance ideal solutions with commercial realities Designed and maintained APIs used by customers or internal teamsOther Skills needed: Solid backend engineering experience in C#, Java, or Go, with a strong grasp of API design and architectureHands-on experience managing and debugging production systems across cloud and self-managed infrastructure.Proven ability to navigate complex third-party integrations, including retry logic and reconciliation workflows.Strong understanding of distributed system resilience - partial failures, retry strategies, and circuit breaker patterns.Why people join: Engineers here are given autonomy in decision making and trusted to do so. You will have the opportunity to work on meaningful technical challenges, influence how systems evolve, and collaborate with experienced colleagues who care about building things properly.The Good Bits:£70,000 - £90,000Hybrid workingExposure to large-scale SaaS platformsClear progression opportunitiesA collaborative engineering culture that values learning and continuous improvementThe chance to work on systems used by thousands of people every dayThe Hard Bits:You will be untangling complexities, improving reliability and leaving systems better than you found them.Careers move quickly. Make sure yours is moving in the right direction.Apply now or get in touch for a confidential conversation.We are an equal opportunity employer and value diversity at our company. We do not discriminate on the basis of race, religion, colour, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.By applying you are confirming you are happy to be added to the Addition Solutions mailing list regarding future suitable positions. You can opt out of this at any time simply by contacting one of our consultants.