Senior Fullstack Engineer (JS/React+Java)

About the Position

Join Intellias to build the next generation of digital banking for 18M users with a focus on evolving an enterprise-grade backend platform for a leading Ukrainian bank. You will design and develop high-quality Java-based applications while ensuring performance and scalability for millions of end users.

Responsibilities7

• Design and develop high-quality Java-based applications.
• Create detailed technical specifications for applications.
• Troubleshoot and debug applications.
• Ensure applications meet performance and scalability requirements.
• Work closely with other teams to ensure the end product meets the client’s needs.
• Monitor application performance and provide optimization recommendations.
• Stay up to date with the latest technologies and industry trends.

Requirements24

• 6+ years of experience building client–server applications, with proven delivery in both frontend and backend.
• Strong FE development experience.
• Strong JavaScript / TypeScript proficiency and solid fundamentals in HTML5, CSS3 (Sass/Less), responsive design, and cross-browser compatibility.
• Strong experience with React and modern frontend tooling, including React Router, Webpack, and component styling (e.g., styled-components).
• State management experience with Redux (and middleware such as Saga, if applicable to the project).
• Experience designing scalable, secure, and performant frontend applications.
• Strong proficiency in Java (Java 21+) and deep understanding of OOP principles.
• Strong hands-on experience with Spring Framework: Spring Boot, Spring Core, Spring Web.
• Solid knowledge of software design patterns, data structures, and application/solution architecture principles.
• Strong knowledge of RESTful services and API design best practices.
• Practical experience with SQL and NoSQL databases.
• Experience with messaging systems such as Kafka and/or RabbitMQ.
• Strong testing skills with JUnit, Mockito (and unit/integration testing practices).
• Understanding of Java Memory Model (JMM) and Garbage Collection (GC).
• Familiarity with build tools: Maven and/or Gradle.
• Proficiency with HTML5 and CSS3 (Sass/Less).
• Expertise in building responsive layouts.
• Principles of cross-browser development.
• Experience in frontend application scalability, performance and security.
• Familiarity with Docker (containerization) and modern delivery practices.
• Proficiency with Git and version control workflows.
• Knowledge of information security principles and secure development practices.
• Experience working with AWS (cloud-native services is a plus).
• Bachelor’s/Master’s degree in Computer Science, Software Engineering, or a related technical field.