4,372 Java Kotlin jobs in the United Kingdom

Job Summary:

We are looking for a skilled Java Backend Developer with strong expertise in Spring Boot and Microservices architecture to join our growing engineering team. The ideal candidate will have hands-on experience building scalable, high-performance backend systems and APIs.

Key Responsibilities:

1. Design, develop, and maintain scalable backend services using Java, Spring Boot, and Microservices.

2. Implement RESTful APIs and integrate with third-party systems.

3. Write clean, maintainable, and testable code following best practices.

4. Collaborate with front-end developers, QA, DevOps, and product teams.

5. Participate in code reviews and mentor junior developers.

6. Troubleshoot production issues and implement fixes.

7. Work with containerization tools like Docker and orchestration tools like Kubernetes.

8. Implement logging, monitoring, and performance tuning.

Required Skills & Experience:

1. 7+ years of hands-on experience in backend development with Java (Java 8 or higher).

2. Strong knowledge and experience with Spring Boot, Spring Cloud, JPA, and Hibernate.

3. Experience in building and consuming RESTful APIs.

4. Strong understanding of Microservices architecture and inter-service communication patterns (REST, messaging).

5. Knowledge of SQL and NoSQL databases (e.g., MySQL, PostgreSQL, MongoDB).

6. Experience with CI/CD pipelines and tools like Jenkins, Git, Maven/Gradle.

7. Familiarity with Docker, Kubernetes, and cloud platforms (AWS, Azure, GCP) is a plus.

8. Understanding of security aspects like OAuth2, JWT, and API security.

We’re seeking a versatile Backend / AI Developer with hands-on experience delivering end-to-end solutions from concept to production. The ideal candidate brings strong expertise in Java (Spring Boot) and Python, with the ability to build scalable microservices, SaaS platforms, and AI-powered applications. You should be proficient in cloud platforms such as AWS and GCP, and experienced in API-first design, security best practices, and observability tools to ensure reliable, high-performing systems.

On the AI side, you have practical experience working with large language models (LLMs), prompt engineering, and frameworks like LangChain, with knowledge of advanced patterns such as Retrieval-Augmented Generation (RAG) and agent-based systems. A strong foundation in Agile SDLC practices is essential, along with familiarity in containerization, DevOps, and low-code/no-code platforms.

Experience across both backend and AI domains will enable you to seamlessly integrate advanced AI capabilities into scalable enterprise systems, making you a key contributor to building the next generation of intelligent, secure, and high-performance applications.

Backend / AI Developer – Key Skills & Competencies

Core Development:
Hands-on experience in taking solutions from concept to production, with strong expertise in Java (Spring Boot) and Python for backend and AI-driven application development.

Proficiency in building microservices, SaaS solutions, and API-first architectures to enable scalable, interoperable systems.

Frameworks & Tools:
Backend: Spring Boot (web, data, cloud, security), JUnit 5, Mockito, database integration.

AI: LangChain, Retrieval-Augmented Generation (RAG), MCP servers (as consumer and developer), and prompt engineering for LLM optimization.

Exposure to popular libraries and frameworks (Apache Commons, Guava, Swagger, TestContainers).

Architecture & Platforms:
Skilled in designing and deploying distributed systems on cloud hyperscalers (AWS, GCP).

Familiarity with containerization (Docker), CI/CD pipelines, DevOps practices, and Infrastructure as Code (IaC).

Experience with workflow/orchestration engines and agent-based architectures.

Scalability, Data & Observability:
Expertise in designing for scalability, performance, and extensibility across structured, semi-structured, and unstructured data.

Strong foundation in security best practices, with practical knowledge of logging, metrics, tracing, distributed debugging, and performance monitoring.

Awareness of AI application security and model safety considerations.

AI Development: 
End-to-end development of AI-powered solutions, from concept to production readiness.

Practical experience with LLMs and agentic AI, including LangChain integration, RAG pipelines, prompt engineering, and model consumption via APIs.

Ability to bridge backend and AI workflows, integrating advanced AI capabilities into scalable enterprise platforms.

SDLC & Agile Practices: 
Familiar with the Software Development Life Cycle (SDLC) and effective collaboration in Agile environments.

Ability to leverage low-code/no-code platforms for rapid solution delivery.

Nice to Have:
Knowledge of Domain-Driven Design (DDD) and schema-first development.

Experience designing plugin architectures and extensibility frameworks.

Exposure to frontend development (HTML5, CSS3, TypeScript, responsive UIs) for full-stack collaboration.

To apply, please submit your CV and daily rate expectation by clicking on the relevant links. If successful you will be contacted by one of our consultants within 3 working days. Unfortunately, due to the volume of applications we expect to receive for this role, if you do not hear from us within this time you should presume your application has been unsuccessful on this occasion.

Grassroots Recruitment is acting as a recruitment agency and a recruitment business in respect of this contract vacancy. Grassroots Recruitment is an equal opportunities employer and recruiter. We welcome applications from all sections of the community, regardless of age, race, sex, sexual orientation, marital status, religion or disability

The Opportunity

We're looking for a talented Senior Backend Developer to join a purpose-driven tech team that creates solutions making a real difference in people's lives. This is more than just a job, it's a chance to shape systems that support individuals and organisations across the UK and Ireland.

The Role

As a Senior Backend Developer, you'll be a founding member of a newly formed cross-functional engineering team. You'll play a key role in setting the tone for the team's culture, practices, and success. Your technical expertise will shape our architecture and support business-critical applications.

This is a highly collaborative role suited to someone with a passion for software craftsmanship and continuous improvement.

Key Responsibilities

• Enhance features and functionality of core products
• Design and implement scalable backend systems using C# (.NET 5+ preferred)
• Write clean, maintainable, and testable code using TDD/BDD principles
• Create and maintain RESTful and GraphQL APIs
• Collaborate with POs, BAs, and stakeholders to define solutions
• Mentor junior developers and promote best practices
• Drive improvements in development processes and tools

What You Bring

• 5+ years of backend development experience
• Expertise in C#, .NET (preferably .NET 6+), and SQL Server
• Deep understanding of SOLID and OOP principles
• Skilled in Git, Unit Testing (NUnit), and API development
• Familiarity with CI/CD pipelines and agile methodologies
• Strong communication and problem-solving skills
• Desire to grow within a dynamic and evolving team

Why Join?

This is an incredible opportunity to make your mark in a company that prioritises purpose, innovation, and professional growth. You'll be part of a team where your ideas are welcomed, your development is encouraged, and your work truly matters.

Ready to build something that helps others-and builds your career in the process? Apply today.

48954MSR1

INDMANS

Senior Backend Developer

Salary: Up to 90,000 per annum
Client: Leading Data Centre Provider

We're working with a well-established Data Centre Provider to recruit a highly experienced Senior Backend Developer. This is a remote role open to UK-based candidates, offering the chance to work on large-scale systems that support critical national infrastructure.

This is an excellent opportunity for a seasoned backend engineer with deep expertise in Node.js and TypeScript, who enjoys architecting scalable solutions and working with modern cloud technologies.

You'll be responsible for designing and building high-performance backend applications, contributing to the development of internal tools and processes, and ensuring code quality through testing and documentation. You'll also help shape technical standards and collaborate closely with other teams across the business.

Key Responsibilities

• Architect and develop scalable backend systems for enterprise-level applications
• Build and maintain robust Node.js services using TypeScript
• Optimise SQL queries and database performance
• Deploy and manage applications in cloud environments
• Customise build and development tools to suit project needs
• Apply best practices in software design, including SOLID principles and dependency injection
• Maintain clean, well-tested, and well-documented code
• Contribute to unit and integration testing across all deliverables
• Work closely with frontend developers to ensure seamless integration
• Stay up to date with emerging trends in backend development and share insights with the team

Required experience

• Extensive server-side development experience
• Strong proficiency in Node.js and TypeScript
• Solid understanding of cloud platforms and deployment strategies
• Deep knowledge of software architecture and design patterns
• Experience with CI/CD pipelines and modern development tooling
• Excellent communication and collaboration skills
• Must be eligible for SC clearance.

This is a brilliant opportunity to join a forward-thinking organisation at the forefront of digital infrastructure. If you're ready to take the next step in your backend development career, we'd love to hear from you.

Paying up to 90,000, depending on experience.

100% remote based.

Must be eligible to work in the UK.

Senior Backend Developer

Salary: Up to 90,000 per annum
Client: Leading Data Centre Provider

We're working with a well-established Data Centre Provider to recruit a highly experienced Senior Backend Developer. This is a remote role open to UK-based candidates, offering the chance to work on large-scale systems that support critical national infrastructure.

This is an excellent opportunity for a seasoned backend engineer with deep expertise in Node.js and TypeScript, who enjoys architecting scalable solutions and working with modern cloud technologies.

You'll be responsible for designing and building high-performance backend applications, contributing to the development of internal tools and processes, and ensuring code quality through testing and documentation. You'll also help shape technical standards and collaborate closely with other teams across the business.

Key Responsibilities

• Architect and develop scalable backend systems for enterprise-level applications
• Build and maintain robust Node.js services using TypeScript
• Optimise SQL queries and database performance
• Deploy and manage applications in cloud environments
• Customise build and development tools to suit project needs
• Apply best practices in software design, including SOLID principles and dependency injection
• Maintain clean, well-tested, and well-documented code
• Contribute to unit and integration testing across all deliverables
• Work closely with frontend developers to ensure seamless integration
• Stay up to date with emerging trends in backend development and share insights with the team

Required experience

• Extensive server-side development experience
• Strong proficiency in Node.js and TypeScript
• Solid understanding of cloud platforms and deployment strategies
• Deep knowledge of software architecture and design patterns
• Experience with CI/CD pipelines and modern development tooling
• Excellent communication and collaboration skills
• Must be eligible for SC clearance.

This is a brilliant opportunity to join a forward-thinking organisation at the forefront of digital infrastructure. If you're ready to take the next step in your backend development career, we'd love to hear from you.

Paying up to 90,000, depending on experience.

100% remote based.

Must be eligible to work in the UK.

We’re seeking a versatile Backend / AI Developer with hands-on experience delivering end-to-end solutions from concept to production. The ideal candidate brings strong expertise in Java (Spring Boot) and Python, with the ability to build scalable microservices, SaaS platforms, and AI-powered applications. You should be proficient in cloud platforms such as AWS and GCP, and experienced in API-first design, security best practices, and observability tools to ensure reliable, high-performing systems.

On the AI side, you have practical experience working with large language models (LLMs), prompt engineering, and frameworks like LangChain, with knowledge of advanced patterns such as Retrieval-Augmented Generation (RAG) and agent-based systems. A strong foundation in Agile SDLC practices is essential, along with familiarity in containerization, DevOps, and low-code/no-code platforms.

Experience across both backend and AI domains will enable you to seamlessly integrate advanced AI capabilities into scalable enterprise systems, making you a key contributor to building the next generation of intelligent, secure, and high-performance applications.

Backend / AI Developer – Key Skills & Competencies

Core Development:
Hands-on experience in taking solutions from concept to production, with strong expertise in Java (Spring Boot) and Python for backend and AI-driven application development.

Proficiency in building microservices, SaaS solutions, and API-first architectures to enable scalable, interoperable systems.

Frameworks & Tools:
Backend: Spring Boot (web, data, cloud, security), JUnit 5, Mockito, database integration.

AI: LangChain, Retrieval-Augmented Generation (RAG), MCP servers (as consumer and developer), and prompt engineering for LLM optimization.

Exposure to popular libraries and frameworks (Apache Commons, Guava, Swagger, TestContainers).

Architecture & Platforms:
Skilled in designing and deploying distributed systems on cloud hyperscalers (AWS, GCP).

Familiarity with containerization (Docker), CI/CD pipelines, DevOps practices, and Infrastructure as Code (IaC).

Experience with workflow/orchestration engines and agent-based architectures.

Scalability, Data & Observability:
Expertise in designing for scalability, performance, and extensibility across structured, semi-structured, and unstructured data.

Strong foundation in security best practices, with practical knowledge of logging, metrics, tracing, distributed debugging, and performance monitoring.

Awareness of AI application security and model safety considerations.

AI Development: 
End-to-end development of AI-powered solutions, from concept to production readiness.

Practical experience with LLMs and agentic AI, including LangChain integration, RAG pipelines, prompt engineering, and model consumption via APIs.

Ability to bridge backend and AI workflows, integrating advanced AI capabilities into scalable enterprise platforms.

SDLC & Agile Practices: 
Familiar with the Software Development Life Cycle (SDLC) and effective collaboration in Agile environments.

Ability to leverage low-code/no-code platforms for rapid solution delivery.

Nice to Have:
Knowledge of Domain-Driven Design (DDD) and schema-first development.

Experience designing plugin architectures and extensibility frameworks.

Exposure to frontend development (HTML5, CSS3, TypeScript, responsive UIs) for full-stack collaboration.

To apply, please submit your CV and daily rate expectation by clicking on the relevant links. If successful you will be contacted by one of our consultants within 3 working days. Unfortunately, due to the volume of applications we expect to receive for this role, if you do not hear from us within this time you should presume your application has been unsuccessful on this occasion.

Grassroots Recruitment is acting as a recruitment agency and a recruitment business in respect of this contract vacancy. Grassroots Recruitment is an equal opportunities employer and recruiter. We welcome applications from all sections of the community, regardless of age, race, sex, sexual orientation, marital status, religion or disability

The Opportunity

We're looking for a talented Senior Backend Developer to join a purpose-driven tech team that creates solutions making a real difference in people's lives. This is more than just a job, it's a chance to shape systems that support individuals and organisations across the UK and Ireland.

The Role

As a Senior Backend Developer, you'll be a founding member of a newly formed cross-functional engineering team. You'll play a key role in setting the tone for the team's culture, practices, and success. Your technical expertise will shape our architecture and support business-critical applications.

This is a highly collaborative role suited to someone with a passion for software craftsmanship and continuous improvement.

Key Responsibilities

• Enhance features and functionality of core products
• Design and implement scalable backend systems using C# (.NET 5+ preferred)
• Write clean, maintainable, and testable code using TDD/BDD principles
• Create and maintain RESTful and GraphQL APIs
• Collaborate with POs, BAs, and stakeholders to define solutions
• Mentor junior developers and promote best practices
• Drive improvements in development processes and tools

What You Bring

• 5+ years of backend development experience
• Expertise in C#, .NET (preferably .NET 6+), and SQL Server
• Deep understanding of SOLID and OOP principles
• Skilled in Git, Unit Testing (NUnit), and API development
• Familiarity with CI/CD pipelines and agile methodologies
• Strong communication and problem-solving skills
• Desire to grow within a dynamic and evolving team

Why Join?

This is an incredible opportunity to make your mark in a company that prioritises purpose, innovation, and professional growth. You'll be part of a team where your ideas are welcomed, your development is encouraged, and your work truly matters.

Ready to build something that helps others-and builds your career in the process? Apply today.

48954MSR1

INDMANS

• Design, develop, and maintain high-performance backend services and APIs.
• Implement and manage database solutions, ensuring data integrity and efficient querying.
• Write clean, well-documented, and testable code following best practices.
• Collaborate with frontend developers to integrate user-facing elements with server-side logic.
• Optimize applications for maximum speed, scalability, and security.
• Participate in code reviews to ensure code quality and share knowledge with the team.
• Troubleshoot and resolve bugs and performance issues.
• Contribute to architectural decisions and technology stack selection.
• Stay up-to-date with emerging backend technologies and industry trends.
• Work closely with product managers and designers to translate requirements into technical solutions.
• Mentor junior developers and contribute to a positive team culture.
• Implement and maintain CI/CD pipelines for automated testing and deployment.

• BSc or MSc in Computer Science, Software Engineering, or a related field.
• 5+ years of professional experience in backend development.
• Proficiency in at least one modern backend programming language (e.g., Python, Java, Node.js, Go, C#).
• Strong experience with relational databases (e.g., PostgreSQL, MySQL) and/or NoSQL databases (e.g., MongoDB, Cassandra).
• Experience with RESTful API design and development.
• Familiarity with cloud platforms (e.g., AWS, Azure, GCP) and containerization technologies (e.g., Docker, Kubernetes).
• Solid understanding of software design patterns and principles.
• Experience with testing frameworks and methodologies.
• Excellent problem-solving and debugging skills.
• Strong communication and collaboration skills, comfortable working in a remote team.
• Experience with Agile development methodologies.