Senior Software Engineer - TypeScript / Next.Js / SQL A growing technology-led business is rebuilding and modernising the core system including billing, invoicing, reconciliation, integrations, operational workflows, reporting, customer tooling, and internal platforms. These systems sit at the heart of the organisation and directly influence revenue, operational efficiency, customer trust, and commercial decision-making. This role is suited to someone who enjoys solving complex operational and data problems, and who takes ownership of outcomes rather than simply delivering tickets. Strong engineering judgement, systems thinking, and an appreciation for correctness are essential in an environment where mistakes can have meaningful downstream impact. AI-assisted development is already central to the engineering workflow. Tools such as Claude Code and Cursor are actively used day-to-day, and senior engineers are expected to use them confidently and pragmatically. What You ll Be Responsible For Designing and evolving business-critical systems across operations, finance, integrations, and customer workflows Leading technical investigations into workflows, operational issues, integrations, and data discrepancies Partnering closely with finance, operations, support, engineering teams, and customers to solve complex business problems Leading technical and operational discussions with customers over calls and video meetings Building systems that are accurate, auditable, explainable,