Full-Stack Engineer — Code QA (Python or JavaScript)

About OpenTrain AI

OpenTrain AI is the #1 platform for building careers in AI training and data labeling. We hire and contract contributors who help shape how modern AI systems learn by preparing, reviewing, and improving the examples these models train on.

We offer flexible, remote roles that let you apply technical skills on real-world AI training projects and grow your experience in a rapidly expanding field.

About AI training and why it matters

AI training (data labeling, annotation, and human feedback work) is the human side of building AI: people annotate code, write and rate model responses, and evaluate test artifacts so models behave reliably.

This is an accessible, cutting-edge way to work remotely and part-time—contributors directly influence model behavior, quality, and safety across many applications.

The role — Full-Stack Software Engineer (QA Reviewer)

You will be a QA-focused Full-Stack Software Engineer conducting in-depth reviews of coding tasks and unit tests to ensure correctness, clarity, and test coverage. This is a fully remote, contractor, part-time role requiring strong technical judgment and written communication.

Workload is flexible but expected to be 20+ hours per week. Compensation is PAY_PER_HOUR at USD 30/hour. You will typically be assigned to review artifacts in one language (Python or JavaScript).

What you’ll do day-to-day

Perform detailed code and unit-test reviews to validate correctness, edge-case coverage, and adherence to best practices.

Identify bugs, redundancies, ambiguous requirements, or missing tests and provide clear, actionable feedback.

Help refine and optimize QA rubrics and review guidelines to improve consistency and reviewer efficiency.

• Verify task correctness and explain why a solution is correct or incorrect.
• Propose improvements to test cases and suggest additional edge cases where appropriate.
• Collaborate with other QA reviewers and stakeholders to resolve ambiguities and scale review processes.

Requirements — what we must see in your application

This position requires professional software development experience, strong testing knowledge, and excellent English communication skills.

Please answer application questions in full sentences and include the specific items requested below; incomplete or yes/no responses may disqualify your application.

• Minimum 5 years of professional full-stack software development experience — in your application, state exactly how many years you have.
• Strong proficiency in Python or JavaScript; state exactly how many years of experience you have with both Python and JavaScript (we will assign you to one language for work).
• Deep understanding of unit testing frameworks and best practices, and experience writing and reviewing unit tests.
• Proven ability to analyze, debug, and evaluate complex codebases and technical artifacts; provide detailed, constructive feedback.
• Exceptional attention to detail and ability to identify gaps, redundancies, and ambiguities in technical tasks and tests.
• Strong written and verbal communication in English. Candidates outside USA, Canada, UK, or Australia must provide documentation demonstrating C1 or C2-level English proficiency (e.g., IELTS, TOEFL, or equivalent).
• Available for at least 20+ hours per week; contractor/part-time engagement.

Preferred qualifications

These are not required but will make your application more competitive.

• Experience with LLM training for code or working on code-annotation projects.
• Prior experience teaching, mentoring, or producing educational annotations for developers.

Interview, tests, and application instructions

Your application must: state exactly how many years of full-stack experience you have; state exact years of experience with Python and with JavaScript; confirm your weekly availability; and, if applicable, attach proof of English C1/C2 proficiency.

At the end of the interview you will be required to answer two technical test questions below. Applicants must provide complete answers before the interview is finished; these answers will factor into your interview score.

• TEST QUESTION 1 — Code Review and Debugging (Python): Review the function, identify at least two issues or improvements, and explain why each is necessary. def calculate_average(numbers): total = 0 for num in numbers: total += num average = total / len(numbers) return average
• TEST QUESTION 2 — Annotating Code for AI Training (JavaScript): Add clear inline comments explaining each line, and note assumptions or edge cases the function might need to handle. function isPalindrome(str) { str = str.toLowerCase().replace(/[^a-z0-9]/g, ''); let reversedStr = str.split('').revers

How to apply

Apply through OpenTrain AI with a brief cover note, your exact years of experience (overall full-stack, years with Python, years with JavaScript), your weekly availability, and any English proficiency documentation if required.

Include concise answers to the test questions above as part of your submission or be prepared to complete them during the interview. We review applications for fit and technical accuracy, then invite selected candidates to a short technical interview and scoring exercise.

• Employment type: Contractor, Part-time. Pay: USD 30/hour. Minimum weekly time: 20+ hours.
• We hire globally; non-US/Canada/UK/Australia applicants must attach proof of C1/C2 English proficiency.