Remote Senior C Systems Explorer & Codebase Reasoner

Mercor; New York (NY); On-site; USD 138,000 - 248,000; Full time

Job summary

Mercor is seeking experienced C engineers to build datasets that teach AI agents to reason about real codebases. You will tackle high-level, multi-file questions on foundational C systems and demonstrate runtime behavior across large projects.

This fully remote role pays per approved task at $130, with tasks drawn from major codebases like PostgreSQL, Redis, git, and OpenSSH. You will document outcomes and iterate through Studio validation loops.

Qualifications

• 3+ years of professional software engineering experience with substantial production C.
• Ability to navigate a large unfamiliar C codebase and explain behavior at runtime.
• Comfort with preprocessor-heavy builds, platform conditionals, manual memory management, and build graphs.
• Experience with databases, cryptography, networking or systems programming is relevant.
• Precise written English: questions and rubrics you write are the product.

Responsibilities

• Select tasks from a pre-validated pool of C repositories, each pinned to a specific git commit and arriving with a question, rubrics, foils, and a golden solution.
• Explore the repository until you understand the subsystem and its PR/history.
• Rewrite the task's question to defeat frontier coding agents while remaining well-defined.
• Adjust rubrics/foils to reward correct reasoning and reject plausible-but-wrong answers.
• Run the full validation loop in Studio — Check, Golden, Run, Analyze — and iterate until all stages pass.
• Document your work in the task README and address reviewer feedback.

Skills

Production C

Large codebase navigation

Debugging & profiling

English writing

Tools

Debugger tools

Sanitizers

Tracing & Profilers

Job description

Mercor is seeking experienced C engineers to build datasets that teach AI agents to reason about real codebases. You will tackle high-level, multi-file questions on foundational C systems and demonstrate runtime behavior across large projects.

This fully remote role pays per approved task at $130, with tasks drawn from major codebases like PostgreSQL, Redis, git, and OpenSSH. You will document outcomes and iterate through Studio validation loops.