Principal Software Development Engineer

We are a technology-driven company building high-performing, scalable, and resilient software solutions. Our teams work with a modern tech stack including .NET, MongoDB, AWS, Jenkins, SQL Server, and streaming technologies. We’re looking for a hands-on Principal Engineer who can code, design scalable systems, manage Staff Engineers, and drive technical excellence across multiple teams. This role is perfect for a technical leader who still enjoys writing code while shaping architecture and mentoring engineers.As a Principal Engineer, you will play a critical role in:Architecting scalable, high-performance systemsCoding and reviewing mission-critical features (at least 60% hands-on)Driving best practices in software development and AI-powered engineeringIf you thrive on solving complex technical challenges, leading by example, and empowering teams, this is the role for you!Hands-on coding (at least 60% of the time), working on core application components and system architectureManaging & mentoring Staff Engineers – supporting career growth and technical excellenceDefining and enforcing non-functional requirements (NFRs) – scalability, security, performanceOptimising CI/CD pipelines with Jenkins & AWSResearching and implementing AI-driven development tools to boost productivityProven experience as a Principal Engineer / Lead Engineer / Software ArchitectProven hands-on coding experience with .NET, SQL Server, MongoDB, Angular/NextJS, AWS, and streaming technologiesStrong experience in building scalable and high-performance applicationsSolid understanding of Test-Driven Development (TDD) and modern testing frameworksExperience with Docker & Kubernetes for containerisation and cloud deploymentStrong knowledge of CI/CD pipelines, automation, and deployment best practicesExperience with AI-assisted development tools is a plusAJ Bell is one of the fastest-growing investment platform businesses in the UK offering an award-winning range of solutions that caters for everyone, from professional financial advisers to DIY investors with little to no experience. We have over 561,000 customers using our award-winning platform propositions to manage assets totalling more than £89.Our customers trust us with their investments, and by continuously striving to make investing easier, we aim to help even more people take control of their financial futures.Starting holiday entitlement of 26 days, increasing up to 31 days with length of service plus a holiday buy and sell schemeA choice of pension schemes with matched contributions up to 7%Discretionary bonus schemeAnnual free share awards schemeHealth Cash Plan – provided by SimplyHealthDiscounted private healthcare scheme and dental planFree gym membershipEmployee Assistance ProgrammeSick pay+ pledgeEnhanced maternity, paternity, and shared parental leaveLoans for travel season ticketsCharitable giving opportunities through salary sacrificeCalendar of social events, including monthly payday drinks, annual Christmas party, summer party and much moreOngoing technical trainingPeer recognition scheme, with rewards including restaurant and shopping vouchers or time offWe believe in building strong connections by working together. That’s why we offer a hybrid working model, where you’ll spend a minimum of 50% of your working time per month in the office. For new team members, an initial period will be full-time in the office to help you immerse yourself in our business and build valuable relationships with your colleagues.We do not discriminate on the basis of race, sex, gender identity, sexual orientation, age, pregnancy, religion, physical and mental disability, marital status, and any other characteristics protected by the Equality Act 2010….