UI Developer ReactJS & TypeScript

Square One Resources; Burgess Hill; On-site; GBP 55,000 - 75,000; Full time

Job summary

Square One Resources is seeking an experienced UI Developer to join a high-performing software engineering team. You will design, develop and test responsive user interfaces using React and TypeScript in an Agile setting.

The role requires strong frontend engineering experience, hands-on work on modern web apps, and collaboration with product, engineering and stakeholders to deliver data-driven digital solutions.

Qualifications

• Strong experience in UI/frontend development.
• Proficient with React JS and TypeScript.
• Hands-on with JavaScript ES6, HTML5 and CSS3.

Responsibilities

• Design and develop modern web applications using React and TypeScript.
• Build dynamic, data-driven UIs including JSON Schema-based forms.
• Develop reusable React components with functional patterns and Hooks.
• Implement state management with Redux and/or Context API.
• Integrate frontend with RESTful APIs and web services.
• Write maintainable code with automated tests (RTL or similar).
• Participate in code reviews and promote engineering best practices.
• Identify and implement frontend performance optimization.
• Collaborate with product and engineering in an Agile environment.
• Mentor engineers when required.

Skills

React JS

TypeScript

JavaScript ES6

HTML5

CSS3

React Hooks

Redux/Context API

RESTful APIs

JSON

Agile

React Testing Library

Tools

React Testing Library

JSON

REST APIs

Job description

UI Developer ReactJS & TypeScript

Location:West Sussex
Office: 3 days per week mandatory
Contract: 12 months
Start Date: By mid-September 2026
Working Hours: 40 hours per week

The Opportunity

We are looking for an experienced UI Developer to join a high-performing software engineering team supporting a leading global financial services organisation. You'll be working on modern, customer-focused digital products and data-driven web applications within a fast-paced, technology-led environment.

You will be responsible for designing, developing, testing and enhancing responsive user interfaces using React and TypeScript, while contributing to high standards of code quality, performance, security and maintainability.

This is a hands-on role suited to someone with strong frontend engineering experience who enjoys working in an Agile product development environment and wants to contribute to innovative digital solutions within a globally recognised financial services business.

Key Responsibilities

• Design and develop modern, scalable web applications using React and TypeScript.
• Build dynamic, data-driven user interfaces and forms, including JSON Schema-based forms.
• Develop reusable React components using functional component patterns and React Hooks.
• Implement effective state management using Redux and/or Context API.
• Integrate frontend applications with RESTful APIs and web services.
• Develop and maintain high-quality application code aligned with industry standards and compliance requirements.
• Write and maintain automated tests using React Testing Library or similar frameworks.
• Participate in code reviews and contribute to engineering best practices.
• Identify and implement web application performance optimisation opportunities.
• Work closely with product, engineering and other stakeholders within an Agile delivery environment.
• Contribute to the mentoring and development of engineering team members where required.

Essential Skills & Experience

• Software engineering/product development experience.
• Strong commercial experience in UI / frontend development.
• Excellent hands-on experience with React JS and TypeScript.
• Strong knowledge of JavaScript ES6, HTML5 and CSS3.
• Experience with React Hooks and functional component architecture.
• Experience with Redux and/or Context API.
• Experience with React Testing Library or comparable frontend testing frameworks.
• Strong experience integrating applications with RESTful APIs.
• Hands-on experience working with JSON and web service technologies.
• Experience developing data-driven UIs and dynamic forms.
• Understanding of frontend performance optimisation techniques.
• Experience working within Agile software development environments.
• Strong understanding of software engineering standards, code quality and maintainability.

Desirable Skills

• Node.js
• Java
• Experience mentoring or supporting other engineers.
• Experience working within distributed engineering teams.
• Professional certifications in software engineering, architecture, or product management.

What We’re Looking For

We're looking for a developer who is not only technically strong but also takes ownership of their work, contributes to engineering standards, and can collaborate effectively across a product-focused environment.