Full Stack Software Engineer, Callsign

Salary not provided

SQL

React

AWS

Docker

Kubernetes

CSS

TypeScript

Redux

GCP

HTML

JavaScript

Java

Kafka

Redis

Linux

Postgres

Figma

Vue.js

MySQL

Cypress

Prometheus

Jest

Spring

Grafana

Yarn

Oracle

SpringBoot

REST API

DynamoDB

Angular 14+

Mid and Senior level

London

2+ days a week in office

Fraud prevention, authentication & intelligence

Be an early applicant

Fraud prevention, authentication & intelligence

201-500 employees

B2BArtificial IntelligenceSecurityDeep TechMachine LearningIdentity

Be an early applicant

Salary not provided

SQL

React

AWS

Docker

Kubernetes

CSS

TypeScript

Redux

GCP

HTML

JavaScript

Java

Kafka

Redis

Linux

Postgres

Figma

Vue.js

MySQL

Cypress

Prometheus

Jest

Spring

Grafana

Yarn

Oracle

SpringBoot

REST API

DynamoDB

Angular 14+

Mid and Senior level

London

2+ days a week in office

201-500 employees

B2BArtificial IntelligenceSecurityDeep TechMachine LearningIdentity

Company mission

To seamlessly power the identification of every web, mobile and physical interaction.

Job

Company

Role

Who you are

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

Desirable

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

What the job involves

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
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

Salary benchmarks

Our take

Callsign uses deep learning technology to analyse a variety of real time signals such as the GPS location, force of touch and screen co-ordinates to identify potentially suspicious usage of a device. Collaborating with Lloyds bank, the company's technology helps to mitigate unauthorised access while providing a seamless user experience.

Callsign is not the only company in this area, and faces competition from other firms such as AimBrain, Behaviosec, and BioCatch. To stand out, its AI system takes into account a combination of different factors to improve its accuracy and reliability. It has also built security in, with all data encrypted on the device itself before being sent to the server.

Steph

Company Specialist at Welcome to the Jungle

Insights

Top investors

18% employee growth in 12 months

Glassdoor (3.1)

Company

Funding (last 2 of 4 rounds)

Jun 2023

$73.9m

LATE VC

Jul 2017

$35m

SERIES A

Total funding: $112.7m

Company benefits

Health & wellbeing: From health insurance to discounted gym memberships to childcare vouchers, we constantly invest in the health and wellbeing of our teams
Learning: Collective growth is one of our core values. Learning opportunities and learning support are core to the Callsign experience
Family benefit: As well as personal health and wellbeing benefits, we also offer various other discounts like home utilities and childcare vouchers
Holidays: In addition to 25 days annual leave (on top of bank holidays), you'll also get an additional Callsign bank holiday in June
Flexible working hours: We've all got different priorities and pressures in our lives. Our flexible working policy will help lighten the load
Multiple locations: We know that different people work best in different environments – that's why we offer opportunities for flexibility in your working environment

Company HQ

City of London, London, UK

Leadership

Zia Hayat

(CEO)

Previously held positions at Accenture, BAE Systems and Lloyds, where he designed and delivered critical military and financial information systems.

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