Full-Stack Developer - AI Trainer (Spain)

Stack

Responsibilities

• ▹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

Requirements

• ▹Advanced professional written proficiency in English
• ▹3–7 years of professional software engineering experience
• ▹Strong proficiency in Python and JavaScript/TypeScript
• ▹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

Nice to have

• ▹Working knowledge of Java, C#, or Go

What we offer

• ▹Flexible, self-managed schedule
• ▹Fully remote work
• ▹Part-time, project-based engagement – you may work with other vendors/employers in parallel

About the company

Anyone AI runs expert evaluation projects in partnership with leading AI labs, engaging experienced software engineers for quality assurance and validation work.