Full-Stack Java Engineer - Scalable APIs & UI

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

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