Backend Developer (Spain)

Role overview Create and review production-realistic coding exercises as a part-time remote consultant. The assignment covers backend and full-stack engineering work, including debugging, feature changes, refactoring or migration, and test creation. Success means producing exercises with unambiguous requirements, correct solutions, and useful validation.

Responsibilities - Develop multi-file tasks that model realistic bugs, feature requests, refactors, migrations, or testing needs. - Translate task goals into clear written specifications and working reference implementations. - Create and improve unit and integration tests that validate expected outputs. - Review peer submissions for soundness, clarity, and practical realism. - Look for edge cases, hidden ambiguities, and ways a solution may fail. - Check that the task description, implementation, and validation artifacts agree, and give actionable review feedback.

Requirements - 3–7 years of professional software engineering experience, including backend or full-stack production systems. - Strong Python and JavaScript or TypeScript skills, with working familiarity in Java, C#, or Go. - Practical experience with testing frameworks such as pytest, Jest, JUnit, xUnit, or Go testing. - Ability to debug and understand large codebases with many files. - Experience participating in code reviews and carrying out refactoring and production migrations. - Advanced written English proficiency.

Benefits and work setup - Remote, part-time consulting on a project basis, with control over your schedule. - Payment is set per project; hourly estimates reflect anticipated completion time. - You provide your own tools and may take on other work where permitted by the applicable organizations.