Java AI Training Developer

About OpenTrain

OpenTrain is the centralized platform where people start and grow careers teaching AI. We connect skilled contributors with code- and data-focused AI training work, help you build a portable portfolio, and make it easy to find, apply for, and manage contract projects.

This role is hired and managed by OpenTrain AI. Creating an OpenTrain account is free and lets you apply, track work, and consolidate your AI training experience.

About AI training work

AI training (data labeling, annotation, and human feedback) is the human side of building modern models. Contributors annotate, evaluate, and curate examples that teach AI how to write, reason, and code.

These jobs are often remote and flexible, accessible without prior industry experience for many roles, and give you direct influence over how state-of-the-art systems behave.

• 100% remote and flexible work—fit tasks around your schedule.
• Great for developers who want hands-on impact in model behavior and alignment.

The role

We’re hiring an intermediate-level Java AI Training Developer to design, implement, and evaluate code-centric artifacts used to train and refine AI models. You will combine software development with hands-on model evaluation and dataset creation to support supervised fine-tuning, RLHF, and reward-model improvement.

This is a contract, part-time position (20+ hours/week). Work is worldwide and conducted in English.

• Employment types: Contractor, Part-time.
• Time commitment: 20+ hours per week.
• Primary data type: Computer code/programming; main label activities: evaluation/rating, RLHF, fine-tuning, code annotation.

What you'll do

• Design, develop, and maintain efficient Java code used in model training pipelines and evaluation tools.
• Benchmark model performance and analyze evaluation results to drive continuous improvement.
• Rank AI model responses to user queries across diverse technical domains and write clear rationales for your judgments.
• Create and maintain task-specific datasets for supervised fine-tuning and support RLHF workflows and reward-model refinement.
• Review code and documentation, provide constructive feedback, and contribute to evaluation strategy.
• Collaborate cross-functionally to improve model alignment, clarity, relevance, and technical accuracy.

Requirements

You must be comfortable writing and reasoning about Java code and translating technical judgment into clear evaluation rationale.

• Strong proficiency with Java syntax and conventions.
• Experience building web apps with modular, scalable architectures and scalable backend code.
• Familiarity with testing, code readability, security, and stability best practices.
• Experience evaluating and ranking AI model responses and writing clear explanations for decisions.
• Familiarity with supervised fine-tuning and RLHF workflows and reward-model improvement.
• Bachelor’s or master’s degree in Engineering, Computer Science, or equivalent experience.
• Prior software QA or test planning experience is a plus.
• Excellent spoken and written English communication skills.
• Availability for 20+ hours per week and ability to work remotely.

How it works / Next steps

If this fits your skills and schedule, create a free OpenTrain account to apply. Your profile will centralize your AI training work and make it easy to track projects and outcomes.

Selection typically includes a short skills screening and sample evaluations or coding tasks so you can demonstrate your Java expertise and judgment on model outputs. OpenTrain handles contracting and project assignment for this role.