Lead Fullstack Engineer

Location: Hybrid (2 office days in London minimum)

Contract Length: 2 Months (with scope for extension)

Interview Process: 1 Stage, MS Teams

We are supporting a next-generation SaaS payment assessment and orchestration platform in hiring a Lead Full Stack Engineer to serve as the technical authority across a modern TypeScript, React and Golang stack. This is a principal-level engineering role at the heart of an ambitious fintech programme, combining Open Banking data, an AI‑driven policy and arbitration engine, and a real‑time payment orchestration layer. The successful candidate will own architecture decisions, set engineering standards and mentor a growing squad of senior and junior engineers from proof of concept through to pilot and beyond. This role suits a hands‑on technical leader with deep full stack experience across TypeScript and Golang, a strong grasp of multi‑tenant SaaS architecture, and the credibility to lead engineering delivery in a fast‑paced, cross‑functional environment.

Key Responsibilities

• Own end-to-end technical design and delivery across the TypeScript, React and Vite front end and Golang microservices, ensuring alignment with the multi-tenant SaaS architecture.
• Define module boundaries, API contracts across REST and gRPC, and state management patterns for the React client, alongside idiomatic Golang service structure, error handling and concurrency patterns for the back end.
• Lead the engineering squad as a hands‑on tech lead, running design reviews, approving pull requests and serving as the primary escalation point for technical blockers.
• Set and enforce standards for TypeScript typing discipline, component architecture, Vite build configuration, unit and integration testing, and Golang test coverage.
• Design and maintain CI/CD pipelines covering front end bundle optimisation, Golang binary builds, containerisation and cloud deployment across all programme workstreams.
• Collaborate with the Lead Architect, Cloud Architect and Data Science teams to integrate machine learning driven affordability and vulnerability models into both the Golang service layer and React UI.
• Partner with the Product Owner and UX Designer to translate FCA-aligned payment and financial strain detection requirements into performant, accessible React interfaces.
• Contribute to principal-level technical governance, providing engineering assurance and risk management across all programme phases.

Requirements

• 5 or more years of full stack engineering, with recent production delivery using TypeScript on the front end (React required, Vite or equivalent modern bundler) and Golang on the back end.
• Deep command of React including component lifecycle, hooks, context, performance optimisation and build tooling with Vite.
• Strong Golang proficiency including idiomatic service design, goroutines and channels, HTTP middleware and dependency management with Go modules.
• Proven experience architecting multi-tenant, API-first SaaS platforms in a cloud-native environment across AWS, Azure or GCP.
• Practical knowledge of Open Banking or PSD2 data standards, payment processing flows or financial services integrations.
• Experience leading engineering squads, establishing code review culture, mentoring mid and junior engineers and driving technical roadmaps.
• Comfortable operating in an Agile delivery environment alongside business analysts, data scientists, security and cloud architects.
• Familiarity with gRPC or GraphQL for front-end and back-end contract design.
• Experience integrating AI and machine learning model outputs within financial services or affordability assessment products.
• Knowledge of FCA Consumer Duty obligations and regulated product delivery.
• Exposure to ETL pipelines, real-time transaction processing or event-driven architectures.