Software Engineer (Full Stack)
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Before you apply
LocationLondon, England, United Kingdom
Typefull-time
SeniorityMid
Experience3–6 yrs
DepartmentTechnology
Company size201–500 people
PostedOct 5, 2026 · 1mo ago
Verified live3h ago
At a glanceSummarised by Seekless from the posting.
3–6 years of commercial full-stack software development experience
Strong backend expertise in Java, Spring Boot, and RESTful API design
Hands-on frontend experience with modern JavaScript or TypeScript frameworks, preferably React
Proficiency in JavaScript, HTML5, CSS3/SCSS, and responsive UI design
Working knowledge of frontend build tools and package managers such as Vite, Webpack, npm, or yarn
Solid experience with relational databases such as MySQL, PostgreSQL, or Oracle, and SQL query writing
Strong understanding of OOP fundamentals, SOLID principles, and data structures and algorithms
Familiarity with testing frameworks across the stack, such as JUnit, Mockito, Jest, React Testing Library, or Cypress
Familiarity with Docker, Linux environments, and CI/CD pipelines
Exposure to microservices architecture
Awareness of secure coding practices including OWASP Top 10, XSS, CSRF prevention, and secure authentication/token management
Strong communication, analytical thinking, and collaboration skills
gRPC experience is a plus
Commercial experience with Vue.js or Angular is also welcome
Experience with Java 17 and Spring WebFlux with Project Reactor, or Java 21+ Virtual Threads
Production experience with NoSQL systems such as DynamoDB
Production experience with TypeScript and modern frontend state management such as Redux Toolkit or Zustand
Familiarity with design systems, component libraries, and tools like Storybook or Figma
Production experience with microservices architecture, distributed caching with Redis, and event streaming with Kafka
Familiarity with container orchestration, Kubernetes, Helm, and cloud platforms such as AWS or GCP
Familiarity with observability and monitoring tools such as Prometheus, Grafana, OpenTelemetry, or Elastic Stack
Basic understanding of web accessibility and web performance optimisation
Skills
Java
Spring Boot
RESTful API
gRPC
JavaScript
TypeScript
React
Vue.js
Angular
HTML5
CSS3/SCSS
Vite
Webpack
npm
yarn
MySQL
PostgreSQL
Oracle
SQL
JUnit
Mockito
Jest
React Testing Library
Cypress
Docker
Linux
CI/CD
Java 17
Spring WebFlux
Project Reactor
Java 21+ Virtual Threads
DynamoDB
Redux Toolkit
Zustand
Storybook
Figma
Redis
Kafka
Kubernetes
Helm
AWS
GCP
Prometheus
Grafana
OpenTelemetry
Elastic Stack
Benefits
Pension
Private medical cover
Life assurance
Learning budget
Cycle to work scheme
Family leave
Annual leave
Volunteering program
About the role
As a Full Stack Software Engineer at Callsign, you will design, build, and maintain end-to-end features spanning our high-throughput Java backend services and modern web interfaces. You’ll work in an Agile, collaborative environment alongside Product, Experience Engineers and QA to deliver secure, scalable, and intuitive digital experiences. You will take ownership of features from architectural design through implementation, testing, deployment, and operational monitoring.
What you’ll do
•
Design, build, and maintain scalable Java-based backend services and modern frontend web applications.
•
Develop robust RESTful APIs and integrate frontend interfaces seamlessly with backend systems.
•
Build responsive, accessible, and performant user interfaces using modern web frameworks.
•
Write clean, testable, and maintainable code across the full stack following engineering best practices.
•
Collaborate closely with Product Managers, UX/UI Designers, QA, and platform teams to translate user requirements into technical solutions.
•
Participate in peer code reviews, contribute to architectural discussions, and proactively address technical debt.
•
Support deployment pipelines, troubleshoot production issues across frontend and backend layers, and drive continuous improvement.
Requirements
•
3–6 years of commercial full-stack software development experience.
•
Strong backend expertise in Java, Spring Boot, and RESTful API design; gRPC experience is a plus.
•
Hands-on frontend experience with modern JavaScript or TypeScript frameworks, preferably React. Commercial experience with Vue.js or Angular is also welcome.
•
Proficiency in JavaScript, HTML5, CSS3/SCSS, and responsive UI design.
•
Working knowledge of frontend build tools and package managers such as Vite, Webpack, npm, or yarn.
•
Solid experience with relational databases such as MySQL, PostgreSQL, or Oracle, and SQL query writing.
•
Strong understanding of OOP fundamentals, SOLID principles, and data structures and algorithms.
•
Familiarity with testing frameworks across the stack, such as JUnit, Mockito, Jest, React Testing Library, or Cypress.
•
Familiarity with Docker, Linux environments, and CI/CD pipelines.
•
Exposure to microservices architecture.
•
Awareness of secure coding practices including OWASP Top 10, XSS, CSRF prevention, and secure authentication/token management.
•
Strong communication, analytical thinking, and collaboration skills.
Good to have :
•
Experience with Java 17 and Spring WebFlux with Project Reactor, or Java 21+ Virtual Threads.
•
Production experience with NoSQL systems such as DynamoDB.
•
Production experience with TypeScript and modern frontend state management such as Redux Toolkit or Zustand.
•
Familiarity with design systems, component libraries, and tools like Storybook or Figma.
•
Production experience with microservices architecture, distributed caching with Redis, and event streaming with Kafka.
•
Familiarity with container orchestration, Kubernetes, Helm, and cloud platforms such as AWS or GCP.
•
Familiarity with observability and monitoring tools such as Prometheus, Grafana, OpenTelemetry, or Elastic Stack.
•
Basic understanding of web accessibility and web performance optimisation
Benefits
Pension scheme with Scottish Widows
Private medical cover with Vitality
Life assurance (4x base salary)
Personal Learning & Development Budget
Cycle to Work Scheme
Company Family Leave
25 days annual leave plus Callsign Bank Holiday
Employee Volunteering Program