Java Developer

A2IT Tecnologia is a Portuguese company specializing in information technology services, founded in 2006. We provide integrations and management of technological solutions, with competence centers available 24x7 and with nationwide coverage. We have offices and support centers in Portugal (Lisbon, Porto, Faro and the Islands), Brazil (Fortaleza and Belo Horizonte) and the United Arab Emirates (Dubai), guaranteeing comprehensive coverage to meet the needs of our clients. We have several partners and are GNS and ISO 9001 certified.

Java Developer (Core Java – Legacy Systems)

Key Responsibilities:

• Design, develop, and maintain backend services using Core Java to implement complex business logic;
• Work within a large, monolithic codebase (~2M lines) and ensure scalability, maintainability, and high performance;
• Apply expertise in multithreading, concurrency, and performance optimization;
• Participate in system design, code reviews, and agile Scrum ceremonies;
• Write clean, testable, and maintainable code using TDD and object-oriented principles;
• Debug, profile, and improve distributed and multi-threaded applications;
• Collaborate with other developers and DBAs to troubleshoot and optimize database interactions;
• Contribute to legacy system modernization and long-term platform refactoring;
• Conduct technical interviews and review take-home coding challenges;
• Uphold and promote engineering best practices and coding standards.

Required Qualifications:

• 3+ years of hands-on Java development experience (Java 8 or Java 17);
• Strong knowledge of Core Java, data structures, algorithms, and OOP design;
• Proven experience with multithreading, concurrency, and low-latency performance tuning;
• Proficiency with relational databases (e.g., Oracle, PostgreSQL), including complex SQL and tuning;
• Experience working with large legacy systems and monolithic architecture;
• Comfortable working without modern frameworks (e.g., no Spring Boot);
• Familiarity with agile/Scrum methodologies and small collaborative teams;
• Strong analytical thinking, problem-solving, and communication skills;

Nice to Have:

• Experience with algorithmic problem-solving in production systems;
• Interest in legacy modernization and long-term cleanup strategies;
• Familiarity with CI/CD, JUnit, Maven, and automated testing tools.

Work Environment:

• Hybrid model: 2 days/week onsite at Spaces, Marquês de Pombal (Lisbon);
• Small agile teams (3–5 people per team), part of a ~20-person engineering group;
• Long-term, high-impact project with business-critical responsibilities.