Senior Frontend Engineer

This role is suitable for a Senior Frontend Engineer with extensive experience building, testing, and scaling React applications using modern JavaScript or TypeScript.

The candidate should be skilled in component architecture, design systems, D3 visualisations, frontend build tools, backend APIs, cloud platforms, CI/CD, and deployment workflows, with strong collaboration and mentoring abilities.

They should be familiar with delivering resilient client-facing applications, translating complex AI and data science insights into accessible interfaces, collaborating with cross-functional teams, and leading frontend engineering standards in high-stakes environments.

How would you structure a scalable React and TypeScript application that presents complex machine learning insights?

I would separate domain logic, data-fetching concerns, and presentational components, using strongly typed interfaces at API boundaries. I would also establish consistent state-management, error-handling, loading, and accessibility patterns so the application remains maintainable as features and teams grow.

How would you design a reusable component library and design system for use across multiple client applications?

I would define design tokens, accessible primitives, composable components, and clear API conventions, then document them with interactive examples. Automated visual, unit, and accessibility testing would help prevent regressions while allowing controlled versioning and adoption.

How would you optimise the performance of a large React application?

I would measure first using browser profiling and real-user metrics, then address issues such as unnecessary re-renders, oversized bundles, inefficient data fetching, and slow rendering. Techniques could include code splitting, lazy loading, memoisation where justified, virtualisation, caching, and server or edge delivery improvements.

How would you build an accessible data visualisation with D3 for users interpreting AI model outputs?

I would use D3 for scales, layouts, and visual calculations while keeping rendering integrated with React’s component model. The visualisation would include semantic labels, keyboard support, colour-safe design, tooltips or summaries, and an equivalent textual or tabular representation for users who cannot access the chart.

How would you handle uncertain, incomplete, or delayed data from a machine learning API?

I would model explicit loading, partial, success, empty, stale, and error states rather than assuming a simple success-or-failure response. The interface should explain uncertainty clearly, provide safe retry or refresh actions, and avoid presenting predictions as facts without appropriate context.

What approach would you take to testing a React application used in a high-stakes public-sector environment?

I would combine unit tests for pure logic, component and integration tests for user behaviour, contract tests for APIs, and end-to-end tests for critical journeys. I would also include accessibility, visual regression, security, and performance checks in CI, prioritising scenarios where incorrect information or actions could cause material harm.

How would you design the frontend integration with a Node.js backend API?

I would define a clear, versioned API contract and generate or maintain shared TypeScript types where practical. The client should centralise authentication, request cancellation, retries, timeouts, response validation, and consistent error mapping instead of duplicating these concerns across components.

How would you improve a Webpack or Babel build pipeline for a growing application?

I would inspect bundle analysis and build timings before making changes, then configure efficient caching, appropriate transpilation targets, code splitting, and asset optimisation. I would ensure development builds remain fast while production builds provide reproducible, minified, source-mapped output with dependency and security checks.

What should a robust CI/CD workflow for a cloud-hosted frontend include?

A pipeline should run formatting, linting, type checking, tests, accessibility checks, and security scanning before producing an immutable build artifact. Deployment should use environment-specific configuration, infrastructure controls, staged promotion, observability, rollback capability, and least-privilege access in AWS, GCP, or Azure.

How would you lead frontend technical decisions and mentor engineers across delivery teams?

I would establish lightweight standards through design discussions, documented decision records, code reviews, and reusable examples rather than imposing unnecessary process. Mentoring would combine pairing, constructive feedback, and ownership opportunities, while considering security, accessibility, delivery constraints, and the needs of public-sector users.

Faculty is a growing AI company helping more than 350 global customers, including government and public-sector organisations, deliver responsible technology with real-world impact. As a Senior Frontend Engineer, you’ll build resilient web applications, bring machine-learning insights to life, create reusable design systems, improve CI/CD workflows, and mentor fellow engineers. The stack includes React, JavaScript/TypeScript, D3, Webpack or Babel, Node.js, cloud platforms such as AWS, GCP or Azure, and modern deployment pipelines; the role is hybrid in London and may require UK Security Clearance and occasional client-site work. Salary is not specified, but this is an excellent opportunity to shape high-impact public services, solve complex technical challenges, and help define frontend engineering practices at an ambitious AI company.