C Software Engineer - Codebase Q&A (Remote)
Listing checked September 11, 2026 · pay as published by Mercor
Overview
Mercor needs experienced C engineers to shape a reinforcement-learning dataset that helps AI agents reason about unfamiliar repositories. Your work centers on Codebase Q&A, an environment where agents explore real software and answer high-level engineering questions that demand runtime evidence, not a quick scan of one file. The task pool pulls from production systems such as PostgreSQL, Redis, OpenSSH, and git, with each repo pinned to a specific commit. You rewrite questions, adjust scoring rubrics, and validate tasks in Mercor Studio. The contract pays $130 per approved task and runs remote.
What You'll Do6
- 1Choose a C repository from the validated pool, working from the pinned commit and its existing engineering question, rubrics, foils, and golden solution.
- 2Dig through the subsystem until you can explain its runtime behavior and trace the relevant PR or issue history.
- 3Rewrite the task question so it challenges frontier coding agents while staying clear and fair to answer.
- 4Tune rubrics and foils to reward sound reasoning and catch answers that look right but fail in practice.
- 5Run the Studio validation sequence: Check, Golden, Run, Analyze. Repeat until each stage passes.
- 6Record your process in the task README, submit for expert review, and revise returned tasks based on reviewer notes.
Requirements6
- 13+ years in professional software engineering, with a strong track record shipping production C.
- 2Proven skill at reading a large unfamiliar C codebase and describing how it behaves at runtime, not just what comments or headers claim.
- 3Comfort with the ugly parts of C systems: preprocessor-heavy builds, platform conditionals, manual memory management, and autotools, CMake, or Meson build graphs.
- 4Background in databases, cryptography, networking protocols, or systems programming. Task mix leans on architecture and system design (39%) and code onboarding (34%), plus a security component.
- 5Hands-on use of debuggers, sanitizers, tracing tools, and profilers to verify what code does.
- 6Clear, precise written English. Your questions and rubrics serve as the final product.
Who Should Apply
An ideal candidate has spent years in production C and can open a project like Redis, libuv, or OpenSSL, then explain a subsystem through both source and runtime evidence. This role fits engineers who enjoy writing precise technical questions and defending their reasoning through rubrics. The work is less suitable for people who prefer building features over analyzing existing systems, or who rely on IDE search without debuggers or tracing. Reviewers reject candidates when their C experience is academic or limited to small projects, because the tasks require navigating sprawling builds and platform conditionals. Weak written English also hurts fit, since the task itself is a question and rubric that another engineer will review.
Salary Insight
The contract pays $130 for each approved task. Pay is task-based, so your total depends on how many tasks pass review. Each submission goes through a second engineer and a super reviewer, which makes approval rate a major factor in effective earnings.
Location
Compensation
$130 fixed
Required Skills
Application Tip
In your application, name a large C codebase you have investigated at runtime, such as PostgreSQL or curl, and describe the debugger, sanitizer, or profiler evidence you used to explain a subsystem. Pair that with a short sample of precise technical writing, because Mercor reviews your questions and rubrics as the deliverable.
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Your resume is scanned against this role’s requirements to check qualification fit.
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3Outcome by email
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