Senior C Code Reviewer (Remote, Contract)

About OpenTrain

OpenTrain is the #1 platform for finding and building careers in AI training and data labeling. Creating an OpenTrain account is free—contributors use the platform to discover projects, build a profile, and apply to work that helps shape how modern AI systems behave.

About AI training work

AI training (data labeling/annotation) is the human side of building intelligent systems: people create, review, and score examples that teach models to write, reason, and code. This role sits at the intersection of software engineering and data-quality: your reviews will directly influence the datasets used to train next-generation code models.

• 100% remote and flexible—fit work around other commitments.
• Many projects require no prior AI experience, but specialized roles reward domain expertise.
• Contributors help shape model behavior through precise, rubric-driven reviews.

The role

We’re hiring a Senior C Code Reviewer to audit annotator reviews of AI-generated C code. You will compile and run submitted snippets inside sandboxed containers, validate they meet the prompt, test them under multiple build flags, and ensure they follow security, correctness, and performance best practices.

This is a contract, part-time role (20+ hours/week). You will correct mis-ratings from annotators, provide concise feedback, and ensure every review aligns with our quality rubric so the labeled data remains reliable for model training.

• Pay: USD $24 per hour.
• Workload: 20+ hours per week (remote, worldwide).
• Employment types: Contractor, Part-time.

What you'll do

Your day-to-day is hands-on code validation and quality assurance of human reviews. Each assignment requires you to reproduce behavior, find defects, and confirm compliance with the prompt and rubric.

• Compile and run C snippets in sandboxed containers across multiple build flags and toolchains.
• Use sanitizers (ASan/UBSan/TSan), Valgrind, gdb/lldb to detect leaks, UB, and concurrency issues.
• Verify absence of undefined behavior, buffer overruns, data races, and other security flaws.
• Assess performance implications and flag opportunities for low-level optimization and cache-friendly design.
• Correct annotator scores, add concise corrective feedback, and document findings per the project rubric.

Requirements

You must meet the core technical and professional requirements below—these come from the project brief and are mandatory.

• 7+ years professional experience in C development, QA, or dedicated code-review roles.
• Deep knowledge of modern C (C11/C18), the C standard library, and common compiler extensions (GCC/Clang).
• Strong memory-management expertise: detect leaks, double-frees, dangling pointers, and undefined behaviour.
• Solid concurrency experience: pthreads and C11 threads, atomics, locks, and lock-free reasoning.
• Advanced debugging and testing skills: ASan/UBSan/TSan, Valgrind, gdb/lldb, and unit-test frameworks (Unity, CMock, Catch2).
• Experience with build systems and toolchains: CMake, Meson, Make, and Dockerised toolchains.
• Familiarity with CI/CD pipelines and code-review workflows (GitHub/GitLab pull/merge requests).
• Proven practice running code in sandbox/container environments to validate functionality and prompt compliance.
• Excellent written English (B2+ CEFR) for clear, precise feedback and mentoring.

Nice-to-have skills

These qualifications are not required but will make an application stand out.

• Experience profiling and low-level tuning with perf, VTune, or similar tools.
• Knowledge of secure-coding mitigations (stack canaries, ASLR) and familiarity with CWE/OWASP patterns.
• Experience with rubric-based scoring, checklist-driven reviews, and ticketing tools (Jira, Asana).
• Background in LLM evaluation, RLHF pipelines, or prior AI/ML data-labeling projects.

Who should apply

Apply if you enjoy deep technical reviews, can quickly reproduce and triage C code issues, and take a security-first approach to code quality. This role suits senior engineers, QA leads, and experienced reviewers who want flexible, impactful work contributing to AI model safety and correctness.

How it works / Apply

If this role fits your background, create a free OpenTrain account, build your profile, and submit an application. Selected reviewers will complete a short validation task to demonstrate sandboxed-build and debugging skills before onboarding.

We match reviewers to projects based on experience and availability; all work is remote and contractor-based.

• You will be required to run code in isolated containers and follow project rubrics exactly.
• Compensation is hourly at the stated rate and paid per the project’s contractor terms.