Software Engineer (Full Stack)
TLDR
Own end-to-end features across high-throughput Java services and modern web interfaces, from architectural design through deployment and monitoring.
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
Benefits
Health Insurance
Private medical cover with Vitality
Learning Budget
Personal Learning & Development Budget
Employee Volunteering Program
Paid Parental Leave
Company Family Leave
Paid Time Off
25 days annual leave plus Callsign Bank Holiday
At Callsign we are changing identity. We are an identity fraud, authorization & authentication company, solving the challenges that organizations face in getting their users on to & interacting with their digital platforms. We use deep learning techniques to combine device, location and behaviour datapoints with dynamic policy management and multi-factor authentication, to verify that the user is who they say they are. Our aim is to make identification more secure and simple – helping everyone to get on with their digital lives in the most seamless and secure way possible. If you’re interested in working for a company that’s changing the face of digital identity globally, then you’re in the right place. We’re a talented team of research scientists, engineers and developers working with the latest technology to help make the digital world a more secure place.Our CultureCallsign is a talented team of people who are passionate about their craft and who care about making the digital world more secure. We work collaboratively, adopting agile principles and methodology to develop a reactive and scalable platform that uses the latest technologies. And with regular boardgames nights, pop-up social activities and company parties, it’s easy to meet new colleagues and feel part of the team.
- Founded
- Founded 2011
- Employees
- 51-200 employees
- Industry
- Internet Software & Services
- Total raised
- $35M raised