Open Source Contributor – Java at Mercor

Open Source Java Contributor | $50–85/hr | Worldwide Remote

Mercor is looking for experienced Java developers with a strong open-source background to join a global network of engineers contributing to AI, data, and enterprise software infrastructure projects. This is a part-time contract role (10–20 hrs/week) ideal for backend specialists who thrive in collaborative, high-impact environments.

Key Responsibilities

• Design challenging coding problems with clear input/output specifications, constraints, and explicit function signatures.
• Develop complete mini-repositories including problem statements, reference solutions, comprehensive unit tests (10–20 cases), and executable test runners.
• Implement clean, production-quality code aligned strictly with test expectations.
• Write high-coverage tests addressing edge cases, invalid inputs, and performance constraints.
• Ensure full executability with no missing dependencies or signature mismatches.

Requirements

• 3–6 years of backend development experience in Java.
• Hands-on experience with Spring Boot, Spring Framework, Micronaut, or Quarkus.
• Proven experience building and maintaining RESTful APIs.
• Working knowledge of microservices architecture.
• Experience with databases: PostgreSQL, MySQL, or MongoDB.
• Proficiency writing unit tests using JUnit and Mockito.
• Familiarity with Docker and CI/CD workflows (GitHub Actions or similar).
• Strong understanding of clean code principles, modular design, and code reviews.
• Comfortable with Git-based collaboration including PRs, issues, and reviews.

Role Details

• Part-time / Contract: 10–20 hours per week.
• High-impact contributions to globally visible, open-source projects.
• Competitive hourly rate: $50–$85/hr based on experience.