Senior Frontend Developer

Rullion; Greater London; Hybrid; GBP 96,432,000 - 151,536,000; Full time

Job summary

Rullion is seeking a Senior Frontend Developer (React Native) to lead complex frontend initiatives in a fast-paced engineering environment in London. You will own critical frontend systems, mentor engineers, and drive technical strategy while balancing performance and maintainability.

The role offers a 6-month contract with hybrid work (1 office day) based in London, Farringdon. You will work on scalable, production-ready code, improve CWV, and contribute to best practices across the team.

Qualifications

• Minimum 5 years' commercial experience in frontend engineering or a similar software role.
• Expert-level knowledge of React, TypeScript and modern frontend architectures.
• Experience optimising frontend performance and improving Core Web Vitals.

Responsibilities

• Lead the planning and delivery of complex frontend projects, translating requirements into technical solutions.
• Take end-to-end ownership of critical applications, ensuring reliability, scalability and maintainability.
• Drive architecture discussions and balance business value with technical health.

Skills

React

TypeScript

React Native

Performance optimization

Testing

Accessibility WCAG 2.1 AA

Security practices

Observability

CI/CD pipelines

Build optimisation

Tools

AWS

Terraform

GitLab CI

Vercel

OpenTelemetry

Sentry

New Relic

Job description

Senior Frontend Developer (React Native)

6 Month contract
40 hours per week
Inside IR35
Hybrid 1 office day

London Farringdon office address: 47-53 Charterhouse St, London, EC1M 6PB

About the Role

We are looking for a highly experienced Senior Frontend Engineer to join a fast-paced and innovative engineering environment, helping to build and scale next-generation digital products and customer experiences. This is an opportunity to work on complex, high-impact applications used by both customers and internal stakeholders, while influencing technical strategy and engineering best practices.

As a senior member of the engineering team, you will take ownership of critical frontend systems, mentor engineers across multiple levels, and drive technical decisions that balance business value with long-term maintainability.

Key Responsibilities

• Lead the planning and delivery of complex frontend projects, translating ambiguous requirements into clear technical solutions.
• Take end-to-end ownership of critical applications, ensuring reliability, scalability, performance, and maintainability.
• Drive technical decision-making and architecture discussions across the team.
• Balance short-term business priorities with long-term technical health and sustainability.
• Manage technical debt strategically and advocate for continuous improvement initiatives.
• Deliver high-quality, production-ready code that is secure, performant, maintainable, and well-tested.
• Lead incident management and troubleshooting activities, implementing preventative measures to improve platform stability.
• Design systems with strong observability, scalability, and operational resilience.
• Create and maintain technical documentation, runbooks, and operational processes.
• Mentor and support engineers through coaching, code reviews, and technical guidance.

Required Skills & Experience

Technical Skills

• Expert-level knowledge of React, TypeScript, and modern frontend architectures.
• Strong understanding of React internals, Server Components, and modern React frameworks including js.
• Deep expertise in state management and data-fetching patterns.
• Proven experience optimising frontend performance and improving Core Web Vitals.
• Strong testing background across unit, integration, and end-to-end testing frameworks.
• Knowledge of accessibility standards, including WCAG 2.1 AA.
• Experience implementing frontend security best practices
• Strong debugging and monitoring experience using observability tools.
• Experience designing and maintaining CI/CD pipelines and deployment processes.
• Understanding of build optimisation and module bundling techniques.

Experience

• Minimum 5 years' commercial experience in frontend engineering or a similar software engineering role.
• Proven track record of delivering complex digital products within agile development environments.

Desired Behaviours

• Strong ownership mentality and accountability for product and system performance.
• Ability to communicate complex technical concepts to both technical and non-technical stakeholders.
• Collaborative approach with experience influencing teams and driving consensus.
• Passion for mentoring and developing other engineers.
• Data-driven decision-making and a pragmatic approach to problem solving.
• Commitment to inclusive, high-performing team cultures.

Technology Stack

Frontend

• React
• js
• TypeScript
• React Native
• Flutter/Dart
• Gatsby

State Management

• Redux Toolkit
• Zustand
• MobX
• TanStack React Query
• SWR
• Apollo Client

UI & Design Systems

• Tailwind CSS
• Styled Components
• Material UI (MUI)
• Radix UI
• Framer Motion
• Custom Design Systems

APIs & Data

• GraphQL
• REST APIs
• Contentful CMS
• React Hook Form
• Zod

Testing

• Vitest
• Jest
• Testing Library
• Playwright
• Storybook
• MSW
• Axe / Pa11y

DevOps & Infrastructure

• AWS
• Terraform
• GitLab CI
• Vercel
• OpenTelemetry
• Sentry
• New Relic

Please note:

Should your application be successful, and you are offered the role, a number of pre-employment checks need to be carried out before your appointment can be confirmed. Any assignment offer with our client will be subject to a satisfactory checking report from the Disclosure Barring Service.

We celebrate and support diversity and are committed to ensuring equal opportunities for both employees and applicants.

Rullion celebrates and supports diversity and is committed to ensuring equal opportunities for both employees and applicants.