Software Engineer

About the Role

We are looking for experienced software engineers to help train and evaluate AI models on real-world programming work. You will build and validate coding tasks, review AI-generated code, and write the reference solutions and tests that models are measured against. Your engineering judgment directly shapes how reliably AI systems write, debug and refactor code.

Key Responsibilities

Design realistic coding tasks (bug fixes, feature implementation, refactoring, performance optimisation) with clear specifications.
Build reproducible environments (Git, Docker) and write automated test suites that verify solutions.
Write high-quality reference solutions and explain the design decisions behind them.
Evaluate AI-generated code for correctness, performance, security and readability.
Rank and compare model outputs and justify your judgments in clear written rationale.
Identify recurring failure patterns in model output and report them to the project team.
Follow project guidelines, take part in calibration and review sessions, and incorporate feedback to keep quality consistent.

Who We're Looking For

Required Qualifications

Degree in computer science or a related field, or equivalent professional experience.
3+ years of professional software engineering experience.
Strong Python, plus at least one of Java, C++, TypeScript, Go or Rust.
Proficiency with Git, Docker and automated testing.
Ability to read and navigate unfamiliar codebases.
Fluent written English and clear technical communication.
Reliable, detail-oriented, and able to work independently and meet deadlines in a remote setting.

Preferred Qualifications

Open-source contributions or code-review experience.
Experience with test automation, CI/CD or developer tooling.
Prior LLM evaluation or data annotation experience.
Experience with large or distributed codebases.

Legal and Compliance Notice

All content you submit must be lawful, and you must have the right to share it.
Do not submit confidential or proprietary material belonging to an employer, client or third party, or personal data without a lawful basis.
Rex may verify identity, credentials, ownership and licensing; may reject or remove any submission; and may report unlawful submissions to the relevant authorities.
Engagement and payment are subject to successful verification and to applicable sanctions, export-control, tax and employment laws.
The contractor agreement will set out ownership and licence terms for the work you deliver (to be confirmed by Rex Legal).

Compensation

USD $65–105 per hour, adjusted by country of residence.