Senior Java Software Engineer

Working time: 9:00PM- 6:00AM Vietnam timeLocation: RemoteInterview Process: 2 Rounds (Online)About the RoleWe are seeking an experienced Senior Java Developer to join a global engineering team working on cutting-edge encryption and cybersecurity technologies. This role involves building a secure online web portal that supports cryptography, cybersecurity, and cryptographic key exchange functions. You will collaborate with international experts across multiple regions and report directly to the Director of Engineering.Key ResponsibilitiesDesign, develop, and maintain high-performance, scalable, and secure Java-based applications.Develop and optimize RESTful APIs within Java-based server environments.Collaborate with global teams to integrate application components into enterprise systems.Conduct unit testing, code reviews, and peer mentoring to ensure code quality and best practices.Implement multi-threaded applications and utilize design patterns such as Singleton, Factory, and Observer.Optimize application performance using caching techniques and Big-O Notation analysis.Deploy and configure Apache Tomcat & Servlet Containers and manage WAR file deployments.Work closely with cloud services (AWS) — EC2, S3, Lambda, RDS — and integrate with relational databases.Design and implement database schemas, stored procedures, and ERD diagrams.Collaborate with QA and DevOps to maintain smooth CI/CD processes and ensure system stability.Required Skills & ExperienceMinimum 8 years of professional experience in Java software development, with a continuous work history (no major gaps).Fluent English (US client)Minimum 3 years of experience developing RESTful APIs in a Java-based server environment.Deep expertise with Java Programming Language (JDK 1.6 – Java 19+) and strong grasp of new features.Mastery of Object-Oriented Programming (OOP), including inheritance, polymorphism, and design patterns.Proficient in multi-threading, semaphores, synchronization, and concurrency control.Strong understanding of data structures (collections, lists, maps, interfaces, sorting functions).Skilled in identifying and refactoring bad code; capable of moderating or leading code reviews.Solid hands-on experience with Apache Tomcat configuration and deployment.Minimum 2 years’ experience with Eclipse IDE and up-to-date proficiency.Working knowledge of Amazon Web Services (AWS) — EC2, S3, Lambda, and RDS.Hands-on experience with MySQL, Oracle, or SQL Server, including stored procedure development.Strong understanding of HTTP methods, response codes, and best practices for REST API design.Proficient with Postman or similar API testing tools; experience working in teams using Jira and Kanban boards.Exceptional attention to detail and strong English communication skills (minimum 8.2 TrueNorth standard).Previous experience working with international or U.S.-based clients is a strong plus.Education & CertificationsBachelor’s Degree in Computer Science, Software Engineering, or a related technical field.Technology certifications (e.g., AWS Certified Developer, Oracle Java Certification) are a plus.Why You’ll Love Working With UsOpportunity to work directly with world-class cryptographic and cybersecurity experts.100% remote global working environment with flexible collaboration across time zones.Competitive rate and long-term engagement with continuous learning opportunities.How to ApplyPlease send your updated CV (in English) to justindoan.work@gmail.com with the subject line: Application – Senior Java Developer.