About OpenTrain

OpenTrain is the #1 platform for building careers in AI training and data labeling. We help people find and grow freelance work that teaches AI systems — from annotating data to evaluating model outputs — and build a unified profile they control.

OpenTrain AI is the hiring and contracting organization for this role; you will contract directly with OpenTrain AI as a remote contributor.

About AI training and why it matters

AI training (aka data labeling or human feedback work) is the human side of building AI: people prepare, evaluate, and critique examples that models learn from. This work is remote-friendly, flexible, and accessible — and contributors directly shape how state-of-the-art systems behave.

This role sits at the intersection of software engineering and AI training: you will evaluate AI-generated technical content so models produce safer, more accurate, and more useful Java code and explanations.

The role

You will evaluate AI-generated Java code, architecture proposals, and technical explanations; identify correctness, performance, and design issues; and produce reference implementations and model answers that guide model learning.

This is a part-time contractor role requiring at least 20 hours per week. Pay is $55 USD per hour. Work is remote but restricted to the countries listed below.

What you'll do day-to-day

Your core responsibility is structured, high-quality review of AI outputs and creating training artifacts that models learn from.

• Review AI-generated Java code, architecture designs, and written explanations for accuracy and clarity.
• Identify logic, performance, concurrency, and design issues in Java responses.
• Write high-quality reference implementations and step-by-step reasoning.
• Rate and compare multiple AI answers using structured rubrics and produce comparative feedback.
• Create and refine prompts and responses used in AI training content.

Requirements

You must have professional, production Java experience and strong written English. Prior experience with AI data training or evaluating AI-generated technical content is a plus but not required.

• Strong professional Java engineering background with production experience.
• Deep knowledge of core Java, concurrency, and the Java Collections Framework.
• Experience with Spring or Spring Boot, REST APIs, and microservice architectures.
• Strong code review habits and systematic debugging or performance-analysis skills.
• Ability to write clear technical explanations and structured feedback in English.
• Detail-oriented judgment when comparing alternative Java solutions.

Logistics, pay, and eligibility

Employment type: Contractor, part-time. Minimum commitment: 20+ hours per week. Pay: $55 USD per hour (hourly, paid by OpenTrain AI).

Language: English required. This role is not worldwide — applicants must be located in one of the eligible countries listed below.

• Eligible countries: VN, TL, TH, SG, PK, PH, NP, MY, LK, KH, ID, BT, BD, DE, IN, BR, US
• Labeling tasks: evaluation rating, text generation, and programming/code evaluation (computer code dataset).

Who should apply

This role is a fit if you are an experienced Java backend engineer who enjoys reading and critiquing code, explaining technical choices, and turning judgments into clear training artifacts that improve AI systems.

Candidates with deep backend experience—especially in concurrency, performance tuning, Spring Boot, and microservices—will be most successful.

• Expert-level Java engineers comfortable producing reference implementations and written reasoning.
• Engineers who can consistently apply objective criteria to compare and rate alternate solutions.

How work is assigned and what to expect

You will receive tasks through OpenTrain AI's contributor workflow: review prompts and model answers, submit ratings and written feedback, and upload reference implementations when requested.

Expect a mix of quick evaluation tasks and longer writing tasks (reference code and detailed explanations). All substantive role details (hours, pay, languages, and country eligibility) are stated above and will be enforced during contracting.