Java Developer

About the role

X2P Solution Co., Ltd. is looking for a Java Developer (9-Month Contract) to join a software modernization project with our enterprise client in Bangkok.

The primary responsibility of this role is to analyze and understand an existing Java/JSP web application and support its migration to a modern web application architecture.

The successful candidate should be comfortable working with legacy Java code, understanding existing business logic and application flows, and collaborating with the project team to migrate the existing system to a new technology stack, including React-based frontend development.

This role is suitable for a developer who is strong in code analysis, troubleshooting, and understanding existing systems, rather than focusing only on greenfield development.

Key responsibilities

• Analyze and understand the existing Java/JSP web application, including source code, business logic, and application flow
• Review legacy code to identify existing functionality, dependencies, interfaces, and technical constraints
• Support the migration of the existing web application to a modern application architecture
• Translate existing application logic and functionality into technical requirements for the new system
• Develop and/or modify Java backend components and APIs required by the new application
• Collaborate with frontend developers working with React
• Support system integration between frontend, backend, database, and external systems
• Troubleshoot issues in both the existing and migrated applications
• Perform code reviews, unit testing, debugging, and defect fixing
• Work closely with BA, Tech Lead, QA, and client teams throughout the migration project
• Ensure migrated functionality maintains the required business behavior of the existing application

What we're looking for

• 3–5+ years of professional Java development experience
• Strong ability to read, analyze, and understand existing Java source code
• Experience with JSP / Servlet-based web applications
• Good understanding of Java web application architecture
• Experience with Java frameworks such as Spring / Spring Boot is preferred
• Understanding of REST API development and integration
• Familiarity with modern frontend frameworks, particularly React, is an advantage
• Experience with legacy system modernization, application migration, or system enhancement projects is highly desirable
• Good SQL and relational database knowledge
• Experience with Git or other version control systems
• Strong debugging, problem-solving, and code analysis skills
• Able to work effectively with cross-functional and client teams
• Good communication skills in Thai; working English is an advantage

Contract details

• Contract duration: 9 months
• Employment type: Contract
• Location: Bangkok
• Project type: Enterprise Web Application Modernization / Migration
• Legacy technology: Java / JSP
• Target architecture: Modern Web Application / React-based frontend
• Opportunity to work on a large-scale enterprise modernization project