Senior Frontend Developer


Company:	Rullion
Salary:	£650 to £700 a day
Hours:	Full-time
Location:	London, EC1M 6PB
Job type:	Contract
Posting date:	25 Sept 2026
Closing date:	16 Oct 2026

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Summary

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

TypeScript

React Native

Flutter/Dart

Gatsby

State Management

Redux Toolkit

Zustand

MobX

TanStack React Query

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

Testing

Vitest

Jest

Testing Library

Playwright

Storybook

Axe / Pa11y

DevOps & Infrastructure

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.

This vacancy is being advertised by Rullion Ltd acting as an employment business.

Since 1978, Rullion has been securing exceptional candidates for a range of clients; from large well-known brands, to SMEs and start-ups. As a family-owned business, Rullion's approach is credible and honest, focused on building long-lasting relationships with both clients and candidates.

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.

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