Sr. Software Engineer, Fullstack (UK)
Confirmed on the employer's own hiring board on Nov 2, 2026. First seen by Alion on Oct 30, 2026.
Job Summary
We're looking for a Senior Full Stack Engineer who thrives at the intersection of craft and scale. You'll design and deliver large-scale, multi-tenant cloud services - with a relentless focus on availability, fault-tolerance, and elegant architecture. You'll set the bar for engineering quality and help elevate those around you.
Responsibilities
Core Engineering & Ownership: Build and own scalable SaaS applications end-to-end - frontend, backend, and data layers. Write production-grade code that is reliable, readable, efficient, and testable. Raise the bar through thoughtful code reviews and comprehensive documentation.
System Architecture: Design future-ready architectures and proactively close gaps before they become problems.
Performance & Reliability: Drive system availability and performance - investigate, analyze, and resolve reliability issues across the stack. Recognize opportunities and advocate for better performance and efficiency of software, systems, and processes across teams.
Shift Left Testing & Quality: You champion a rigorous 'shift-left' quality culture, embedding comprehensive testing-unit, integration, and contract-early and continuously in the development lifecycle, not as an afterthought.
AI Integration: Leverage and advocate for AI-assisted tools (e.g., GitHub Copilot, Claude) to accelerate development while maintaining rigorous engineering judgment and accountability for code correctness.
Leadership: Drive team-wide best practices, conduct quality code reviews, and mentor engineers to elevate overall engineering quality.
Collaboration (Product & Design): Partner with Product and Design to translate requirements into intuitive UI, making informed technical trade-offs in the face of ambiguity.
Collaboration (Engineering Standards): Champion engineering best practices across teams and collaborate on solving complex, high-impact problems.
Minimum Qualifications
Bachelor's degree in Computer Science or related field, or equivalent experience.
8+ years building reliable, performant applications and microservices in production environments. Proven full stack fluency - you're comfortable across frontend, backend, and the database layer.
A polyglot mindset - you evolve with the tech. Familiarity with Ruby on Rails, TypeScript, Node.js, Go, or React.js is a strong plus.
Proven full-stack experience across frontend (React.js), backend, and database layers.
Contribute to production health, including on-call rotations and incident response, in a "you build it, you run it" environment.
Technical depth in at least one engineering domain: distributed systems, multi-tenant SaaS, application databases, networking, security, serverless, event streaming, or similar.
A genuine drive to build beautiful, intuitive products with the customer always in focus. Innate curiosity - you love learning and have a desire to teach and lift others. Strong communication skills and openness to collaborative idea-sharing across teams.
Preferred Qualifications:
Core Stack Experience: Familiarity with Ruby (including Ruby on Rails), TypeScript, Node.js, Go, or React.js is a strong plus.