Javascript Developer

OneAPPS Consulting; Burgess Hill; Hybrid; GBP 68,000 - 108,000; Full time

Job summary

OneAPPS Consulting, a London-based technology consulting firm, seeks a senior React Developer to design, develop and maintain modern web applications using React and TypeScript.

You will build data-driven UIs, create reusable components with Hooks, manage state with Redux, and integrate with RESTful APIs in an Agile delivery environment. The role includes mentoring engineers and delivering high-quality, scalable frontend solutions.

Qualifications

• Software engineering or product development experience.
• Strong commercial experience in UI/Front End 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 Front End 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 Front End performance optimisation techniques.
• Experience working within Agile software development environments.
• Strong understanding of software engineering standards, code quality and maintainability.
• Node.js.
• Java.
• Experience mentoring or supporting other engineers.
• Experience working within distributed engineering teams.
• Professional certifications in software engineering, architecture, or product management.

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 Front End 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.

Skills

Front End development

React.js

TypeScript

RESTful APIs

JSON

Agile

Testing

Code quality

Mentoring

Distributed teams

Tools

React

Redux

TypeScript

NodeJS

Java

HTML5

ES6

Job description

Salary: £68,000 - 108,000 per year

Requirements

• Software engineering or product development experience.
• Strong commercial experience in UI/Front End 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 Front End 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 Front End performance optimisation techniques.
• Experience working within Agile software development environments.
• Strong understanding of software engineering standards, code quality and maintainability.
• Node.js.
• Java.
• Experience mentoring or supporting other engineers.
• Experience working within distributed engineering teams.
• Professional certifications in software engineering, architecture, or product management.

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 Front End 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.

Technologies

• API
• ES6
• HTML5
• JSON
• Java
• JavaScript
• React
• Redux
• TypeScript
• Web
• UX UI Design
• NodeJS
• Support
• Security

More

We are OneAPPS Consulting, a technology consulting firm based in London with offices across Europe and more than 7 locations worldwide. We work on diverse projects with multicultural teams and clients across Europe, supporting the growth of our clients and helping deliver projects smoothly. We are seeking an experienced React Developer to join a high-performing software engineering team supporting a leading global financial services organisation. This is a hybrid/onsite role based in Burgess Hill, Essex, with three days per week in the office, an initial 12-month extendable contract, and an immediate start.

last updated 38 week of 2026