Summary: Join as a Middle/Senior Java Engineer to transform Oman's national tax system, driving architectural changes and modernizing core components within an international team. Highlights: 1. Participate in large-scale, national-level government project 2. Influence system architecture and key technical decisions 3. Work within an international team and professional engineering environment Introduct Group is an international technology company delivering tailored software solutions and digital products for businesses worldwide. We work on complex, large\-scale projects across multiple industries, helping clients turn ideas into reliable, scalable systems. We are seeking a Middle/Senior Java Engineer to join a large\-scale international project focused on modernizing Oman's national tax system. The project is undergoing a deep technological transformation aimed at moving from a legacy monolithic architecture to a modular, service\-oriented system built on modern enterprise principles. The Java Engineer will play a key role in developing the backend platform, driving architectural changes, and introducing new core system components. The role involves regular business trips to Oman , with on\-site work periods of up to one month , combined with remote collaboration within an international team. Requirements 3\+ years of commercial experience in Java development. Strong knowledge of the Spring Framework (Spring Boot, REST). Experience designing and developing REST APIs. Experience working with relational databases. Understanding of modular and service\-oriented architecture (SOA) principles. Experience working with legacy codebases and participating in architectural changes. Experience writing unit tests and understanding TDD principles. Solid experience with Maven. Fluent English, both spoken and written. Responsibilities Participate in the architectural transformation and evolution of the backend platform. Develop and refactor REST APIs and backend services using Java and Spring. Contribute to the modernization of core system components (BPM, IAM, business rules). Optimize backend performance and background processing. Participate in CI/CD processes and automated deployments. Collaborate with frontend, DevOps, QA teams, and client representatives. Provide technical leadership and mentorship to junior developers : support solution design; perform code reviews, define and track development tasks, promote and improve engineering best practices within the team. Nice to have Experience using Drools or other rule engines. Experience integrating Keycloak or other IAM solutions. Experience working with Liquibase. Knowledge of Quartz or other job scheduling frameworks. Experience working on large\-scale enterprise or government projects. What we offer Participation in a large\-scale, national\-level government project. Business trips to Oman (up to one month) for on\-site collaboration with the client and project team. Long\-term project with stable collaboration. Accommodation provided. Transportation cost compensation. Relocation and onboarding support. Opportunity to directly influence system architecture and key technical decisions. Work within an international team and a professional engineering environment. Modern enterprise technology stack and technically challenging tasks. Location World\-wide