4,557 Js Developer jobs in the United Kingdom

Job Title

React JS Developer

Get The Future You Want!

Choosing Capgemini means choosing a company where you will be empowered to shape your career in the way you’d like, where you’ll be supported and inspired by a collaborative community of colleagues around the world, and where you’ll be able to reimagine what’s possible. Join us and help the world’s leading organizations unlock the value of technology and build a more sustainable, more inclusive world

Role Overview:

We are seeking a skilled and passionate UI Developer with strong front-end development experience to join our team. The ideal candidate will have hands-on expertise in modern UI technologies and frameworks, with a keen eye for detail and a commitment to delivering accessible, high-performance web applications.

Your Role

• Develop and maintain responsive user interfaces using JavaScript, jQuery, HTML5, CSS3, and ReactJS and other UI technologies
• Implement and optimize styles using CSS preprocessors such as SASS or LESS.
• Work with JavaScript frameworks including Node.js to build scalable front-end solutions.
• Integrate APIs and handle asynchronous data using AJAX and JSON.
• Ensure compliance with accessibility standards and best practices.
• Apply Test-Driven Development (TDD) principles and write automated unit tests using mock object frameworks.
• Collaborate with cross-functional teams to ensure seamless integration and deployment.
• Utilize SCM tools like Git and Perforce for version control and collaboration.
• Leverage tools such as SonarQube, Grunt/Gulp, and npm for code quality and build automation.
• Conduct JavaScript unit testing to ensure code reliability and maintainability.
• Optimize network performance and front-end load times for enhanced user experience.

Your Profile

• Strong proficiency in JavaScript, HTML5, CSS3, and ReactJS.
• Experience with CSS preprocessors (e.g., SASS, LESS).
• Solid understanding of Node.js and modern JS frameworks.
• Familiarity with AJAX, JSON, and RESTful APIs.
• Knowledge of accessibility standards (WCAG, ARIA).
• Experience with unit testing frameworks and TDD methodologies.
• Proficiency in Git, Perforce, and build tools like Grunt, Gulp, and npm.
• Understanding of network performance optimization techniques.

About Capgemini

Capgemini is a global business and technology transformation partner, helping organizations to accelerate their dual transition to a digital and sustainable world while creating tangible impact for enterprises and society. It is a responsible and diverse group of 350,000 team members in more than 50 countries. With its strong over 55-year heritage, Capgemini is trusted by its clients to unlock the value of technology to address the entire breadth of their business needs. It delivers end-to-end services and solutions leveraging strengths from strategy and design to engineering, all fueled by its market-leading capabilities in AI, cloud, and data, combined with its deep industry expertise and partner ecosystem. The Group reported 2023 global revenues of €22.5 billion.

Role: Python Software Engineer

Salary: up to £80k + Bonus + Excellent Benefits

Location: Oxford (Hybrid, very flexible)

We’re hiring on behalf of a global biotech innovator developing groundbreaking technology that enables real-time biological analysis at scale.

This is your opportunity to work at the intersection of science and software , building the systems behind next-generation sequencing and data platforms from portable lab devices to large-scale research infrastructure used by institutions worldwide.

The Role

You’ll join a collaborative international engineering team developing and maintaining high-impact data applications that support critical scientific and commercial operations.

You’ll work on systems that process large biological datasets , support telemetry pipelines , and help deliver cutting-edge tools for researchers and scientists around the world.

What You’ll Do

• Design, build and maintain data-intensive web applications and APIs
• Develop scalable systems using Python (Django, FastAPI, Flask)
• Deploy and manage applications across on-premise and cloud environments
• Implement CI/CD, automated testing, and containerisation best practices
• Collaborate closely with R&D, operations, and scientific teams to ensure reliability and performance

You’ll Succeed If You Have

• Strong, production-level experience with Python
• A background in building web apps, APIs, or workflow engines
• Hands-on experience with Docker , CI/CD pipelines , and cloud-native environments
• Knowledge of databases (SQL, MongoDB) and data pipelines
• Familiarity with Kubernetes , Terraform , or related orchestration tools

What’s on offer:

• Competitive salary and bonus
• Private healthcare & pension
• Collaborative, mission-driven culture

If you’re a Python Software Engineer who thrives in fast-paced, meaningful environments and wants to contribute to technology that’s reshaping global research - apply now.

Role: Full-Stack Developer
Salary: £50,000 - £55,000
Location: London - Hybrid (3 days office / 2 days home)

Our client is a fast-growing consultancy helping organisations in the legal sector embrace digital transformation. They deliver scalable, secure applications by combining expertise in software development, data, and automation.

They are seeking a Full-Stack Developer to join their expanding team. This is a chance to work across the stack, experiment with new technologies, and grow as the company scales.

The role will involve:

• Building, testing, and maintaining full-stack applications
• Collaborating with stakeholders to gather requirements and shape solutions
• Developing scalable apps with modern frameworks and low-code platforms
• Prototyping and experimenting with new technologies
• Working in agile teams to deliver high-quality software

What you'll bring:

• 2+ years' experience in software development
• Proficiency in Python, JavaScript, or C#
• Knowledge of relational databases and RESTful APIs
• Strong problem-solving and communication skills
• Curiosity and eagerness to learn

What's on offer:

• Hybrid working in central London (Covent Garden/Soho/Southbank)
• Competitive salary + private medical insurance + Cycle to Work scheme
• Modern office with gym, showers, and bike storage
• A supportive, collaborative environment where everyone makes an impact

If you're passionate about building great software and want to be part of a growing consultancy, apply today.

Roles and responsibilities of the assignment:

Self-Service Check-in

Development and maintenance of SSCI applications Kiosk and Web Check-ins

Key Deliverables:

• Develop and maintain backend components using C++11 or above, including performance-critical modules.
• Build dynamic and responsive frontend interfaces using AngularJS/Angular 2+ .
• Debug, maintain, and enhance existing systems with a focus on long-term stability and performance.
• Collaborate with cross-functional teams, including PO, PDEF, QA, DevOps, and product stakeholders, to define, design, and deliver new features.
• Refactor legacy code and participate in technical debt reduction.
• Write clean, scalable, and maintainable code with proper documentation.
• Participate in code reviews and mentor junior developers where applicable.
• Ensure secure coding practices and adherence to software development standards.
• Investigate and resolve production issues as part of ongoing product support.

Skills

• 5+ years of professional experience in software development.
• Proficient in C++11 or later, with a strong understanding of memory management, concurrency, and object-oriented design .
• Hands-on experience with AngularJS and front-end development (HTML, CSS, JavaScript ).
• Familiarity with REST APIs , JSON , and web service integration .
• Experience working in software maintenance/support roles with bug fixing and system enhancements.
• Strong debugging and problem-solving skills across the stack.
• Familiar with version control systems such as Git.
• Worked earlier on Scrum models like Kanban or Sprint , have experience working in a team and support team collaboration

Industry Knowledge

• Full-stack Software development

Education:

• Bachelor’s/Master’s degree in Computer Science, Engineering, or a related field.

About Us

A leading international provider of solutions and expertise, specialising in the fields of digital systems and business performance

The SCALIAN Group provides support to major industrial and service-sector companies to help them define and implement their projects in two fields:

Digital Systems Embedded and critical systems, IoT, information systems, and digital solutions for businesses Operations Performance: Management of projects, quality, and industrial performance We are present in seven countries (France, Spain, Belgium, UK, Germany, USA and Canada).

Please Note: Any offer of employment is subject to satisfactory SC security clearance which requires 5 years continuous UK address history, typically including no periods of 30 consecutive days or more spent outside of the UK.

Note: The above information relates to a specific client requirement

Accenture is a leading global professional services company, providing a broad range of services in strategy and consulting, interactive, technology and operations, with digital capabilities across all of these services. With our thought leadership and culture of innovation, we apply industry expertise, diverse skill sets and next-generation technology to each business challenge.

We believe in inclusion and diversity and supporting the whole person. Our core values comprise of Stewardship, Best People, Client Value Creation, One Global Network, Respect for the Individual and Integrity. Year after year, Accenture is recognized worldwide not just for business performance but for inclusion and diversity too.

“Across the globe, one thing is universally true of the people of Accenture: We care deeply about what we do and the impact we have with our clients and with the communities in which we work and live. It is personal to all of us.” – Julie Sweet, Accenture CEO

As a team:

Accenture Software & Platform Engineering is powered by a community of 1,000+ experts and provides end-to-end product engineering solutions which deliver tangible value, fast. We bring together an obsession for technical excellence with agility and scale, to help clients move from project to product at speed.

We partner with clients across all sectors—from fast-growing scale-ups to national and global blue-chip companies, as well as public sector organizations. Our teams regularly develop products that reach and impact millions of users.

As a member of our Software & Platform Engineering team, you will:

• Develop traditional and serverless applications and services in an agile and collaborative environment using source control that integrate with data storage services / message buses and other architectural elements
• Deploy these applications using features such as containers to cloud leveraging CI/CD to support this process backed with good observability when running these in production
• Ensure quality through the creation of documentation and use of unit / integration / contract testing with a consideration of security / performance requirements

We are looking for experience in the following skills:

• A few years of industry experience in one of following: Java / Typescript / C# / Python / Go.
• Experience with Cloud Native technologies on AWS.
• Hands-on experience in scripting languages such as Python, Shell, and other scripting languages to support DevOps and Quality Engineering work.
• Build automation tools to support CI/CD pipeline.
• Hands-on experience with GenAI, or evidence of actively pursuing personal GenAI projects outside of work.
• Strong Accessibility, Security, Performance and Caching coding.

Set yourself apart:

• Experience with building datastore solutions on at least one No-SQL(Elasticsearch).
• Proven ability to apply analytical and creative thought and translate into technical solutions.
• Proven ability to debug and resolve complex technical issues.
• Excellent leadership, communication (written and oral) and interpersonal skills.
• Experience shaping and delivering small to medium size pieces of work.

What is in it for you

At Accenture in addition to a competitive basic salary, you will also have an extensive benefits package which includes up to 25 days’ vacation per year, private medical insurance and 3 extra days leave per year for charitable work of your choice!

Flexibility and mobility are required to deliver this role as there will be requirements to spend time onsite with our clients and partners to enable delivery of the first-class services we are known for.

Equal Employment Opportunity Statement

We believe that no one should be discriminated against because of their differences. All employment decisions shall be made without regard to age, race, creed, color, religion, sex, national origin, ancestry, disability status, military veteran status, sexual orientation, gender identity or expression, genetic information, marital status, citizenship status or any other basis as protected by applicable law. Our rich diversity makes us more innovative, more competitive, and more creative, which helps us better serve our clients and our communities.

Software Engineer

Location: Bishops Stortford

Salary: Up to £50k

Do you have two years software development experience?

Do you have a strong foundation in C# development? Would you enjoy working on projects that involve data integrations, security systems, and enterprise-scale solutions?

This role is ideal for someone with around 2 years’ experience, looking to build on their skills with mentoring from senior engineers.

The Company

Our client is a fast-growing technology business that designs and delivers bespoke software solutions, data integrations, and consultancy services. Since their launch in 2020, they have built a strong reputation for developing custom integrations between third-party systems and access control/security platforms, supporting sectors including higher education, commercial real estate, healthcare, and defence.

Now part of a larger international group, they are expanding their UK-based engineering team and looking for a Software Engineer with skills in C# and SQL to join them. You’ll be working closely with senior engineers, gaining hands-on experience, and supporting clients across the UK, Europe, and North America.

What you will be doing

As C# Software Engineer, you will:

• Design and develop automated unit, regression, and integration tests
• Develop and test backend services across both cloud and on-premise deployments
• Design and implement new features as the product suite evolves
• Deploy custom solutions remotely to client systems
• Investigate and resolve software support issues, including customer-facing interaction
• Write technical documentation and produce supporting materials
• Contribute to code reviews, improving quality and learning from senior colleagues
• Collaborate with end users and partners to ensure smooth delivery

You will be mentored by experienced engineers and have the chance to work with clients ranging from universities to global Fortune 100 and FTSE 250 companies.

What we are looking for

We are looking for someone with a solid technical foundation, an eagerness to learn, and strong communication skills. The ideal candidate will have:

• 2+ years’ professional experience in C# development
• Strong understanding of Computer Science fundamentals (data structures, networking, concurrency)
• Knowledge of OOP principles
• Experience working with APIs (building and consuming)
• Proficiency with Microsoft SQL Server or similar DBMS
• Basic familiarity with GIT or another source control system
• Clear and confident written and spoken English for remote collaboration
• Ability to prioritise, stay organised, and work well under pressure
• Permission to live and work full-time in the UK (visa sponsorship not available)

It’s also a bonus if you have:

• A degree in a scientific or technical discipline from a leading university
• Experience in a customer-facing role
• A proactive and curious mindset, keen to explore new technologies

Why apply?

This is a fantastic opportunity to progress your Software Development career with a company that will invest in your growth. You will gain exposure to varied projects, work alongside experienced engineers, and develop your skills in a supportive, innovative environment.

Hi ,

Greetings from Ampstek !

We do have opening for our client,

Role : Senior UI Developer (React & Angular)

Location : Belfast, NI

Duration : Permanent

Job Description:

Total IT Experience: 7 to 12 years

• Angular / React UI developers with proficiency in Design Systems. Eg: Material UI
• Experience in using the Design system
• Strong experience with React 18+, TypeScript, and ES6.
• Expertise in performance fine-tuning and optimization of front-end applications
• Hands-on experience with React Hooks such as useState, useEffect, useMemo, useCallback, and custom hooks.
• Strong understanding of responsive design principles, patterns, and libraries such as Bootstrap.
• Solid knowledge and hands-on experience in backend API integration, exception handling, and managing synchronous/asynchronous requests
• Proficient in HTML5, CSS3, and modern CSS frameworks like Tailwind CSS or Styled Components.
• Strong experience with Application Security concepts such as Authentication, Authorization, and Data Security.
• Experience in designing applications for multiple browsers and multiple resolutions, including mobile devices.
• Strong experience in responsive design principles and patterns and libraries such as bootstrap.
• Hands-on experience with code release processes, bundling, and packaging applications for production environments.
• Strong skills in troubleshooting front-end issues and adhering to best practices.
• Proven ability to develop reusable components/widgets and implement component-driven architecture and design principles.
• Exposure to unit testing or testing automation frameworks for front-end validation.
• Advanced experience with testing frameworks such as Jest, React Testing Library, Cypress, or Enzyme for unit, integration, and end-to-end testing.
• Strong understanding of web accessibility standards (WCAG) and experience in building inclusive and accessible applications.
• Experience in accessibility testing
• TFS (Team Foundation Server) familiarity will be an added advantage
• Working knowledge of Webpack, Vite, Create React App (CRA), and Agile Scrum Framework for efficient development, build optimization, and project management.
• Familiarity with NGRX or RXJS frameworks, as well as Saga/Thunk patterns for state management and data transfer.
• Exposure to micro-frontends architecture for modular UI development is an added advantage.
• Good to have: Experience in Node.js backend development.
• Familiarity with Continuous Integration methodologies and tools like Jenkins.
• Good to have exposure to cloud CDN and static website hosting in AWS or Azure.
• Excellent communication and presentation skills.

Full Stack Software Engineer (Java/AWS focus)

Location: Plymouth (Remote/Flexible)

Salary: Up to £70,000 depending on experience

Eligibility: Must be eligible for UK Security Clearance (SC)

We’re looking for a Full Stack Software Engineer to join a dynamic, agile environment delivering complex and high-impact software solutions. You’ll help design and build bespoke systems that provide cutting-edge capability to our customers, using modern technologies and engineering best practices.

What You’ll Do

• Design, develop, and test high-quality software solutions
• Work with a wide range of technologies, particularly open-source tools and frameworks
• Build and maintain CI/CD pipelines using GitLab to ensure software quality and security
• Deploy solutions to public and private cloud environments (AWS , Azure )
• Collaborate with cross-functional teams in an Agile environment
• (Depending on experience) Lead technical teams and engage directly with clients

About You

• Essential: Commercial experience with Java and AWS
• Frontend: Experience with JavaScript , TypeScript , or React (at least one required)
• Familiarity with DevOps practices and CI/CD tools (GitLab preferred)
• Experience working in Agile teams
• Consultancy or client-facing experience is advantageous

If you’re a Full Stack Engineer who thrives on solving complex problems and delivering quality software , apply today.

Full Stack Software Engineer (Java/AWS focus)

Location: Cheltenham (Remote/Flexible)

Salary: Up to £70,000 depending on experience

Eligibility: Must be eligible for UK Security Clearance (SC)

We’re looking for a Full Stack Software Engineer to join a dynamic, agile environment delivering complex and high-impact software solutions. You’ll help design and build bespoke systems that provide cutting-edge capability to our customers, using modern technologies and engineering best practices.

What You’ll Do

• Design, develop, and test high-quality software solutions
• Work with a wide range of technologies, particularly open-source tools and frameworks
• Build and maintain CI/CD pipelines using GitLab to ensure software quality and security
• Deploy solutions to public and private cloud environments (AWS , Azure )
• Collaborate with cross-functional teams in an Agile environment
• (Depending on experience) Lead technical teams and engage directly with clients

About You

• Essential: Commercial experience with Java and AWS
• Frontend: Experience with JavaScript , TypeScript , or React (at least one required)
• Familiarity with DevOps practices and CI/CD tools (GitLab preferred)
• Experience working in Agile teams
• Consultancy or client-facing experience is advantageous

If you’re a Full Stack Engineer who thrives on solving complex problems and delivering quality software , apply today.