Senior Software Engineer

Our client is a well-established charity that mobilises volunteers to support individuals, local communities and public health services across the UK. They have developed a volunteering platform. Your role is to be the skilled and motivated Senior Engineer who helps guide the design, development, and delivery of the platform's Next.js front-end. Reporting to the CTO, you'll manage a small team of offshore engineers in your time zone while actively contributing to code, architectural decisions, and quality outcomes yourself. Our client's engineering today is a mix of hands-on development and AI-assisted coding, without disciplined TDD. You'll work directly with the CTO and the other Senior Engineer to move the team to an AI-assisted + TDD way of working — specs and tests agreed up front, AI coding agents handling the bulk of initial implementation, and engineering time increasingly spent on quality: refactoring, verification and system assurance rather than hands-on typing. You'll be critical for setting this standard, both by example in your own code and at each code review, especially in how rigorously AI-generated output is verified before it ships. We're looking for someone who has already worked this way and can bring that discipline in from day one — the benchmark we're aiming for is how leading AI labs build software. You'll thrive here if you enjoy the shift from author to architect and editor — defining intent, catching what AI misses, and raising the bar for the team around you. What you will be doing Hands-On Development Design, build and maintain features primarily in Next.js, React and TypeScript Write clean, testable code that adheres to team standards Partner with team members to debug issues and deliver robust solutions Driving the AI-Assisted + TDD Transition Work with the CTO and the other Senior Engineer to establish spec-first, test-first practices across the team Help define what "spec and tests agreed before coding starts" looks like in practice Coach engineers through the shift from ad hoc AI-assisted coding to disciplined TDD Spec & Test-First Discipline Contribute to and validate the specification (stories, acceptance criteria, architecture, UI, data structures) before coding starts, so decisions are made once and not relitigated mid-sprint Write or review unit tests against the spec ahead of implementation Use AI coding agents (e.g. Claude Code, GitHub Copilot) to accelerate implementation once spec and tests are agreed Quality, Refactoring & Assurance Treat QA, refactoring and system health as the majority of engineering time, not an afterthought Verify AI-generated code for correctness, security and maintainability rather than assuming it's right Use tooling such as SonarQube to maintain code quality Raise blockers early Technical Guidance & Mentorship Line-manage and provide technical leadership to a small team of offshore engineers in your timezone Keep the team aligned with project goals and technical standards Give complete, thought-through feedback during code review and handover Model the spec-first, test-first approach by example Collaboration & Communication Work closely with Product, Design and QA across the feature and story delivery flow Proactively engage — raise questions or problems rather than waiting to be asked Be available for quick syncs during the day Clearly communicate progress, risks and technical decisions to the CTO and relevant stakeholders What you need to know Knowledge Strong experience in front-end development with Next.js, React and TypeScript Component architecture, server-side rendering/static generation, and modern Next.js patterns (e.g. App Router, server components) RESTful API integration from the front-end Deep, practical understanding of test-driven development (TDD) — writing unit tests against a spec before implementation, not after AI-assisted, agentic coding workflows and tools (e.g. Claude Code, GitHub Copilot), including how leading AI labs apply these practices to their own engineering, and how to critically verify AI-generated output CI/CD pipelines and code quality tooling (e.g. SonarQube) Strong problem-solving skills and comfort working in a spec-first, collaborative environment Skills Next.js, React, TypeScript, JavaScript, Nest.js for back-end RESTful APIs, API integration Test-driven development and unit testing frameworks (e.g. Jest, React Testing Library) — end-to-end/Cypress testing sits with the Automated QA function, so this role collaborates with them on coverage rather than owning it directly AI coding agents/assistants (e.g. Claude Code, GitHub Copilot) used in a disciplined, spec-first workflow Coaching and embedding new engineering practices within a team Git, GitHub, CI/CD (e.g. Azure DevOps) Code quality and static analysis tooling (e.g. SonarQube) Design-system implementation and Figma-to-code workflows Clear written and verbal communication Experience 8+ years of engineering experience, with strong recent focus on front-end/Next.js or React development. Experience with Nest.js for back-end is a plus. Proven experience working in an AI-assisted + TDD development workflow — not just AI-assisted coding, but disciplined test-first practice — ideally close to how Anthropic and similar organisations build software Experience leading or actively driving a team’s transition to a new engineering methodology, not just working within an established one 1-2 years experience managing or mentoring developers, ideally in an offshore/distributed team setup Bachelor’s degree in Computer Science, Software Engineering or a related field (or equivalent experience) Experience collaborating closely with Product, Design and QA in a fast-moving, sprint-based environment Comfort setting technical direction directly with the CTO, without a Tech Lead layer in between Track record of shipping production features end-to-end, from spec through to release