Software Engineer (Full Stack)

Callsign; Greater London; On-site; GBP 70,000 - 110,000; Full time

Benefits offered by this job

Pension scheme

Private medical cover

Life assurance (4x base salary)

Learning budget

Cycle to Work

Family Leave

25 days annual leave + holidays

Volunteer program

Job summary

Callsign is seeking a Full Stack Software Engineer to design, build, and maintain end-to-end features spanning high-throughput Java backend services and modern web interfaces. You will take ownership of features from architectural design through implementation, testing, deployment, and operational monitoring.

You will collaborate with Product, UX/UI Designers, QA and platform teams to translate user requirements into technical solutions; write clean, testable code across the full stack and

Qualifications

• 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/TypeScript frameworks (React preferred; Vue/Angular welcome).
• Proficiency in JavaScript, HTML5, CSS3/SCSS, and responsive UI design.
• Familiarity with testing frameworks (JUnit, Mockito, Jest, RTL, or Cypress).
• Familiarity with Docker, Linux environments, and CI/CD pipelines.

Responsibilities

• Design, build, and maintain scalable Java-based backend services and modern frontend web applications.
• Develop robust RESTful APIs and integrate frontend interfaces 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 with Product Managers, UX/UI Designers, QA, and platform teams to translate requirements into technical solutions.
• Participate in peer code reviews and architectural discussions; address technical debt.
• Support deployment pipelines, troubleshoot production issues across frontend and backend layers, and drive continuous improvement.

Skills

Java backend

Spring Boot

RESTful APIs

Frontend JS/TS

React

Vue/Angular

Docker

CI/CD

SQL

OOP/SOLID

Tools

Jenkins

Git

Webpack/Vite

Job description

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.

• 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

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