Java Engineer – Application / Database Modernization (Freelancer)

Mactores is looking for a Software Engineer with proficiency in Java, Spring, and Hibernate to participate in the migration project from Oracle to PostgreSQL. The ideal candidate should possess a robust understanding of Java, Spring, and Hibernate, with hands-on experience in developing large-scale Java web applications.

What you will do?

- Analyze and remediate large enterprise Java codebases to replace legacy or database-specific SQL constructs with modern, standards-compliant SQL.

- Convert embedded SQL within Java services and MyBatis XML mappers, including rewriting constructs such as vendor-specific functions, sequences, pagination logic, dynamic SQL, and error-handling patterns.

- Collaborate closely with schema and database migration engineers to ensure application-layer SQL aligns with the modernized target schema.

- Refactor Java transaction logic, error-handling, drivers, and ORM/DAO layers to support the behavior of modern databases.

- Participate in unit, integration, and performance testing to confirm functional parity and ensure applications meet performance SLAs post-modernization.

- Support application cutover activities for production environments, including validation, monitoring setup, rollback planning, and stabilization.

- Produce engineering documentation: SQL remediation guides, code-migration runbooks, troubleshooting guides, and knowledge-transfer material for customer teams.

- Work across distributed teams (US & India) and collaborate with customer SMEs to ensure business logic alignment and successful modernization outcomes.

What are we looking for?

- Bachelor’s degree in Computer Science, Engineering, or related field.

- 3+ years of professional Java development experience (Spring, JDBC, MyBatis/Hibernate or equivalent).

- Experience with application modernization, database migrations, or large-scale refactoring initiatives.

- Strong SQL expertise and the ability to analyze, interpret, optimize, and rewrite complex SQL used within Java applications.

- Deep understanding of JDBC, ORMs, Java transaction patterns, and database-driven application flows.

- Experience working on enterprise-grade, high-performance applications with complex data interactions.

- Strong communication skills and ability to work with global distributed teams in US time-zones.

You will be preferred if

- Experience with PostgreSQL, Aurora PostgreSQL, or modernization from legacy databases such as Oracle, SQL Server, or DB2.

- Exposure to automated code-refactoring tools or GenAI-assisted remediation workflows.

- Familiarity with CI/CD environments, performance testing tools, and observability stacks.

- Consulting or professional services experience delivering fixed-timeline modernization projects.

Life at Mactores
 
We care about creating a culture that makes a real difference in the lives of every Mactorian. Our 10 Core Leadership Principles that honor Decision-making, Leadership, Collaboration, and Curiosity drive how we work.
 
1. Be one step ahead
2. Deliver the best
3. Be bold
4. Pay attention to the detail
5. Enjoy the challenge
6. Be curious and take action
7. Take leadership
8. Own it
9. Deliver value
10. Be collaborative
 
We would like you to read more details about the work culture on https://mactores.com/careers 
 
 
The Path to Joining the Mactores Team
At Mactores, our recruitment process is structured around three distinct stages:
 
Pre-Employment Assessment: 
A series of evaluations of your technical proficiency and suitability for the role.
 
Managerial Interview: The hiring manager engages with you in multiple discussions, 30 minutes to an hour each, covering technical skills, hands-on experience, leadership potential, and communication. 
 
HR Discussion: During this 30-minute session, you'll have the opportunity to discuss the offer and next steps with a member of the HR team.
 
Mactores provides equal opportunities in all employment practices. We don't discriminate based on race, religion, gender, national origin, age, disability, marital status, military status, genetic information, or any other category protected by federal, state, and local laws. This applies to every part of the employment relationship, recruitment, compensation, promotions, transfers, disciplinary action, layoff, training, and social and recreational programs.
 
 
Note: Please answer as many questions as possible with this application to accelerate the hiring process.