About Kairostek

At Kairostek, we believe great technology starts with great people.

We foster a culture of innovation, collaboration, and continuous growth, empowering our team to make a meaningful impact while building solutions that shape the future. Our teams work across software engineering, artificial intelligence, cloud infrastructure, cybersecurity, digital products, payments technology, and technology operations to deliver scalable and innovative solutions for global organizations.

If you are passionate about technology, problem-solving, and continuous learning, we would love to hear from you.

About the Role

We are looking for a Senior Java Developer who can take ownership of complex payment-platform components, design robust APIs, solve distributed-system challenges, and collaborate with Leads and Architects to deliver scalable and secure solutions.

Key Responsibilities

• Design and develop scalable payment services and APIs using Java 18–25 and Spring Framework / Spring Boot.

• Design clean, maintainable solutions using SOLID principles, design patterns, and modern architecture practices.

• Design and optimize data solutions using PostgreSQL, MySQL, Hibernate/JPA, and Redis.

• Build event-driven and asynchronous processing using Apache Kafka and RabbitMQ.

• Design secure REST APIs using JWT, authentication, authorization, OAuth 2.0/2.1, and API-security principles.

• Apply cryptographic algorithms, hashing, encryption, digital signatures, and secure-data handling.

• Apply OWASP principles and secure software-development practices.

• Develop comprehensive unit, functional, and integration tests using JUnit and Mockito.

• Own Maven/Gradle multi-module builds, dependency management, wrappers, artifact management, and Nexus publishing.

• Contribute to CI/CD automation, Docker/containerization, and cloud deployments.

• Perform technical feasibility studies and evaluate technologies for upcoming features.

• Investigate complex production issues and perform cross-service root-cause analysis.

• Lead refactoring, performance optimization, scalability, and reliability improvements.

• Conduct code reviews and establish development best practices.

• Collaborate with Technical Leads, Architects, Product Managers, and Business Stakeholders.

• Mentor junior developers and support technical knowledge sharing.

• Evaluate AI-assisted development and automation opportunities to improve engineering productivity.

Qualifications & Experience

Java 18–25 • Spring/Spring Boot • REST APIs • Hibernate/JPA • PostgreSQL • MySQL • Redis • Kafka • RabbitMQ • JWT • OAuth 2.0/2.1 • Authentication • Authorization • API Security • Cryptographic Algorithms • OWASP • Maven • Gradle • Nexus • JUnit • Mockito • Git/GitHub • CI/CD • Docker • Cloud • Agile/Scrum/Kanban

Qualifications & Experience

• Bachelor's degree in computer science or equivalent experience.

• 4–8 years of professional Java development experience.

• Strong experience designing enterprise applications and REST APIs.

• Strong understanding of distributed systems, databases, messaging, caching, and security.

• Strong problem-solving and production troubleshooting skills.

• Experience mentoring developers and driving technical improvements.

• Payment/FinTech experience is highly desirable.

What We Offer

• Competitive compensation package.

• Flexible and remote-friendly work environment.

• Professional growth and development opportunities.

• Exposure to international projects and teams.

• Collaborative and inclusive company culture.

• Opportunity to work with modern technologies and innovative solutions.

Equal Opportunity Employer

Kairostek is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We welcome applications from qualified candidates regardless of race, ethnicity, gender, age, disability, religion, sexual orientation, or background.