Senior C Code Reviewer (Security-Focused)

About OpenTrain AI

OpenTrain AI is the #1 platform for people building careers in AI training and data labeling. We connect skilled contributors with meaningful, remote work that directly shapes how state-of-the-art models behave.

We hire contributors as contractors on projects that require careful human judgment and technical expertise. For this role, OpenTrain AI is the hiring and contracting organization and will provide the rubric, sandbox environment, and task workflow.

About AI training and this work

AI training (also called data labeling or human feedback work) is the human side of building AI systems. Contributors validate, correct, and rate examples that models learn from — here, that means assessing and improving reviews of generated C code.

This work is remote-friendly, flexible, and accessible to experienced engineers. It’s a chance to apply deep C expertise to improve model behavior and annotation quality used to train next‑generation systems.

The role

You will audit annotator reviews of AI-generated C code and ensure every review aligns with our quality rubric. Each submission requires hands-on validation: compiling and running the snippet in a sandboxed container, testing under multiple build flags, and checking for correctness, performance, and security issues.

This is a part-time contractor role of 20+ hours per week, fully remote and open worldwide. Compensation is pay-per-hour at USD 24/hour.

What you'll do day-to-day

Your primary responsibilities are practical validation, quality control, and clear feedback. You will correct mis-ratings, supply concise written feedback, and use a rubric-driven approach to keep annotation consistent and reliable.

• Compile and run submitted C code in sandboxed containers across different build flags and optimization levels.
• Verify that the code meets the prompt, functions correctly, and handles edge cases.
• Detect and report undefined behavior, buffer overruns, data races, leaks, and other security or correctness issues.
• Apply sanitizers (ASan/UBSan/TSan), Valgrind, gdb/lldb, and unit tests to validate behavior.
• Correct annotator ratings when they are wrong and provide concise, actionable feedback aligned to the quality rubric.

Required qualifications

You must have strong, demonstrable C expertise and a security-first mindset. Clear written English is essential for precise feedback and rubric-driven scoring.

• 7+ years professional experience in C (C11/C18) development, QA, or dedicated code-review roles.
• Deep knowledge of the C standard library, compiler extensions (GCC/Clang), and common build systems (CMake, Meson, Make).
• Expert memory-management and concurrency skills: detect leaks, double-frees, dangling pointers, data races, and UB; strong grasp of atomics and locks.
• Advanced use of sanitizers, Valgrind, gdb/lldb, and unit-test frameworks (Unity, CMock, Catch2).
• Experience profiling and performance tuning (perf, VTune) and designing cache-friendly low-level code.
• Security expertise: identify CWEs (buffer overflows, integer wrap, format-string issues) and know mitigations (ASLR, stack canaries).
• Comfortable compiling and running code in sandbox/container environments to validate functionality and prompt compliance.
• Excellent written English (B2+ CEFR) for concise feedback and mentoring.

Nice-to-have

These are not required but will help you excel and unlock higher-value tasks.

• Familiarity with CI/CD pipelines and Dockerized toolchains.
• Prior experience with rubric-based QA, ticketing systems (Jira, Asana), or code-review platforms (GitHub/GitLab).
• Background in LLM evaluation, RLHF pipelines, or prior AI/ML data-labeling projects.

How the work is organized

Tasks are delivered through OpenTrain’s workflows. Each submission includes the generated code, the annotator’s review, and the prompt. You will follow checklists and a scoring rubric to make corrections and record feedback.

OpenTrain provides the sandboxed environment and tooling guidelines; you are expected to use the provided containers and recommended tools to validate behavior safely.

• Part-time contractor role; expected 20+ hours/week with flexible scheduling.
• Pay rate: USD 24 per hour, paid per timesheet as a contractor.
• Work is fully remote and open worldwide; no specific country or language restrictions listed.

Who should apply

Apply if you are a senior C engineer, security-minded reviewer, or QA specialist who enjoys hands-on debugging and clear technical communication. This role fits people who like mentorship, rubric-driven QA, and directly improving the data that trains AI systems.

• You enjoy deep technical validation and writing concise, actionable feedback.
• You can work independently as a contractor and commit to consistent weekly hours.
• You are comfortable using sandboxed environments and standard C toolchains.