Full-Stack Developer - AI Trainer (Spain)

Anyone AI is recruiting skilled Full-Stack Developers to work on a project with a leading AI lab.

• Advanced professional written proficiency in English

• 3-7 years of professional software engineering experience

• Strong proficiency in Python and JavaScript/TypeScript; working knowledge of Java, C#, or Go

• Backend or full-stack development experience in production systems

• Experience with testing frameworks (e.g., pytest, Jest, JUnit, xUnit, Go testing)

• Proven ability to debug and navigate large, multi-file codebases

• Experience with code reviews, refactoring, and production migrations

Part-time, project-based expert evaluation work

Remote

Contributors will design and evaluate realistic software engineering tasks, including bug resolution, feature implementation, refactoring/migration, and test generation. Work includes both creating complex coding scenarios and reviewing peer submissions for quality and accuracy.

This is a project-based consultant role. Consultants will be paid on a per-project basis; hourly rates are estimates based on anticipated completion time. Consultants control their own schedule, provide their own tools, and may simultaneously provide services to other vendors/employers (subject to those vendors' allowances).

Contributors will:

• Design and implement multi-file coding tasks across bug fixing, feature development, refactoring, and testing

• Write clear natural-language specifications and reference implementations

• Develop and extend unit and integration test suites

• Review peer-generated tasks for correctness, clarity, and realism

• Identify edge cases, ambiguities, and potential failure modes

• Ensure alignment between specifications, code, and expected outputs

• High-quality, production-realistic coding tasks

• Complete and correct reference implementations

• Robust test coverage and validation artifacts

• Structured, actionable peer review feedback