Java Backend Developer for AI Systems

About OpenTrain

OpenTrain is the #1 platform for finding and building careers in AI training and data labeling. The platform helps people discover AI training projects, build a unified portfolio of work, and grow a durable freelance career teaching AI.

Creating an OpenTrain account is free and gives you access to projects where human expertise directly shapes how AI systems learn and behave.

Why AI Training Work Matters

AI training (also called data labeling or human feedback work) is the human side of building modern AI: people prepare and review the examples that models learn from. This work is remote-friendly, often part-time and flexible, and gives you a direct role in how state-of-the-art systems perform.

Many contributors start with domain skills like programming and expand into higher-paying or specialist projects as they build experience in the industry.

The Role

OpenTrain is recruiting a Java Developer to contribute to training next-generation AI systems by designing and maintaining high-quality backend services that support AI workflows. This is a contractor, part-time role requiring a minimum of 20 hours per week and is open to candidates worldwide.

The role emphasizes applying existing Java development expertise—especially with Spring Boot and microservices—to shape how AI models are supported by reliable backend infrastructure.

• Employment type: Contractor, Part-time
• Time requirement: 20+ hours/week
• Location: Remote, worldwide (English required)

What You'll Do

• Design, develop, and maintain scalable backend systems using Java and Spring Boot.
• Architect robust microservices solutions to support complex application requirements.
• Collaborate with project teams to review technical specifications and deliver high-quality code.
• Contribute expert insights to improve application performance, reliability, and security.
• Participate in code reviews and provide constructive feedback to peers.
• Document technical processes and solutions with clear, concise written communication.
• Troubleshoot, debug, and optimize backend systems as needed.

Requirements

Candidates must meet the required skills listed below; these are essential for performing the role and will be used to evaluate applicants.

• Expert proficiency in Java programming language.
• Hands-on experience with Spring Boot framework for backend development.
• Strong knowledge of microservices architecture and design principles.
• Demonstrated ability to write clean, maintainable, and efficient code.
• Exceptional written and verbal communication skills with attention to detail.
• Experience collaborating with remote teams.

Helpful Background (Nice to Have)

• Exposure to cloud platforms such as AWS, Azure, or Google Cloud.
• Prior experience working on AI-driven or data-intensive projects.
• Background in high-availability or distributed systems.

Compensation & Schedule

This role pays between $30 and $90 USD per hour (hourly pay). The position is offered on a contractor, part-time basis; you should expect to work at least 20 hours per week.

OpenTrain will determine specific hours and scheduling within the contractor arrangement; the role is remote and open to applicants worldwide who meet the requirements.

How to Apply

If this role matches your skills and availability, create a free OpenTrain account and submit your application through the platform so OpenTrain can review your profile and experience.

Include your Java/Spring Boot experience and any relevant links or examples of backend work when you apply.