Senior Software Engineer (Full Stack) Java React

Zühlke Engineering; Greater London; Hybrid; GBP 51,000 - 91,000; Full time

Job summary

Zühlke Engineering is seeking a backend engineer in London or Manchester to build and maintain JVM-based services using Kotlin or modern Java, and to design APIs that power responsive web interfaces.

You will work in a cross-functional squad, apply test-driven practices, and explore AI-assisted tools to improve tests, documentation, and systems while ensuring security, reliability and performance. Occasional client-site work is expected.

Qualifications

• Strong commercial experience building server-side apps with Kotlin/Java.
• Good knowledge of JVM ecosystem and backend practices.
• Experience designing, building and operating APIs.
• Understanding of reliability, performance, security.
• Proven ability to write effective automated tests.
• Practical experience with relational databases.
• Frontend experience with React/TypeScript is a plus.
• Familiar with CI/CD and production support.
• Experience in agile, product-focused teams.
• Interest in AI-augmented engineering and new ways of working.
• Commitment to code quality and continuous improvement.

Responsibilities

• Build and maintain JVM-based services using Kotlin or modern Java.
• Design, develop and document APIs and integrations.
• Contribute to API design standards and docs.
• Deliver end-to-end features with backend services and responsive UI.
• Apply test-first or test-informed practices for automated tests.
• Explore AI-assisted tools where value is clear and safe to use.
• Validate AI outputs for correctness, security and maintainability.
• Contribute to event-driven workflows and asynchronous processing.
• Engage in technical discovery, spikes, architecture discussions and code reviews.
• Improve build, test and deployment pipelines for safe delivery.
• Embed logging, metrics and tracing for operability.
• Consider security and governance in engineering decisions.
• Address technical debt and reliability risks.
• Share knowledge and support a collaborative team culture.
• Work with clients on-site when required to shape solutions and support delivery.

Skills

Kotlin

Java 17+

JVM ecosystem

API design

Automated testing

Relational databases

React

TypeScript

CI/CD

Agile

AI curiosity

Code quality

Tools

Ktor

Spring

Spring Boot

React

TypeScript

AWS

Azure

GCP

NoSQL

SQL

Quarkus

Job description

Salary: £51,000 - 91,000 per year

Requirements:

• Strong commercial experience developing server-side applications with Kotlin or modern Java, ideally Java 17 or later.
• Good knowledge of the JVM ecosystem and common backend development practices.
• Experience designing, building and operating APIs.
• Understanding of service reliability, maintainability, performance and security.
• Proven experience writing effective automated tests.
• Practical experience with relational databases.
• Experience with modern frontend development, ideally using React and TypeScript.
• Familiarity with CI/CD practices and supporting software in production.
• Experience working collaboratively in an agile, product-focused engineering team.
• Curiosity about AI-augmented engineering and a willingness to develop new ways of working.
• A thoughtful approach to code quality, technical trade-offs and continuous improvement.
• Equivalent experience with comparable technologies will be considered.

Responsibilities:

• Build and maintain reliable JVM-based services using Kotlin or modern Java.
• Design and develop APIs and integrations following industry standards.
• Contribute to API design standards and documentation.
• Deliver complete end-to-end features by connecting backend services and data with responsive web interfaces.
• Use applicable test-first and test-informed practices to create effective automated tests.
• Experiment with AI-assisted engineering tools where they provide clear value, such as exploring solutions, improving tests, documenting systems or investigating issues.
• Validate AI-assisted outputs for correctness, security, maintainability, and suitability before using them.
• Contribute to event-driven workflows and asynchronous processing.
• Participate in technical discovery, spikes, architecture discussions and peer code reviews.
• Improve build, test and deployment pipelines to support safe and efficient delivery.
• Embed structured logging, metrics and distributed tracing to make services easier to operate and troubleshoot.
• Consider the operational, security and governance implications of engineering decisions, particularly in complex or regulated environments.
• Identify and address technical debt, performance issues and reliability risks.
• Share knowledge, support collective code ownership and contribute to a collaborative, low-ego team culture.
• Work as part of a cross-functional engineering squad alongside product, design and delivery colleagues.
• Take ownership of significant features and services, contribute to technical decisions, support other engineers and help maintain high standards of engineering quality.
• Work on-site with clients when required, collaborating directly with client stakeholders and delivery teams to understand needs, shape technical solutions and support delivery.

Technologies:

• AI
• API
• Backend
• CI/CD
• Frontend
• Support
• JVM
• Java
• Kotlin
• React
• Security
• TypeScript
• Web
• AWS
• Azure
• Cloud
• Excel
• GCP
• Ktor
• NoSQL
• Quarkus
• Spring
• Spring Boot
• Fullstack

More:

We are Zühlke, founded in Switzerland in 1968 and owned by our partners, with a presence across Europe and Asia. We are a global transformation partner with engineering and innovation at our core, helping clients build future-ready businesses through tech strategy, digital solutions, and device and systems engineering. We work in complex, regulated sectors including health and finance, and offer a collaborative, inclusive environment with flexible working hours, the possibility to work from home, a profit share scheme, and strong investment in development. This role is based in London or Manchester and is full time, with occasional travel or agreed on-site working depending on the project and client needs.

last updated 36 week of 2026