C Software Developer - Fully Remote | Upto $130/task Task based

Obsidian; San Francisco (CA); Remote; USD 60,000 - 120,000; Full time

Job summary

Mercor is seeking experienced C engineers to build a dataset that teaches AI agents to reason about real codebases. You will work on challenging C projects, exploring large codebases and their histories across production repositories.

This fully remote role pays per approved task and operates within Mercor Studio, with experts across multiple time zones. You will contribute to high-stakes tasks requiring careful analysis and precise documentation.

Qualifications

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

Responsibilities

• Select tasks from a pre-validated pool of C repositories, each pinned to a specific git commit.
• Explore the repository to understand the subsystem and relevant history.
• Rewrite tasks to defeat frontier agents while staying well-defined.
• Adjust rubrics and foils to reward correct reasoning.
• Run the full validation loop in Studio and iterate until it passes.
• Document work in task README and address reviewer feedback.

Skills

C programming

Codebase navigation

Debugging and profiling

Written English precision

Job description

1. Role Overview

Mercor is seeking experienced C engineers to build the dataset that teaches AI agents to reason about real codebases.

Codebase Q&A is a reinforcement-learning environment for training AI agents to explore and reason about software repositories they have never seen before. You will build difficult codebase-exploration tasks: high-level engineering questions about foundational C systems that cannot be answered by reading a single file, and that require runtime evidence to resolve — the kind of question a senior engineer answers by actually investigating the system.

This track works on some of the most consequential C codebases in production anywhere: PostgreSQL, Redis, git, OpenSSH, OpenSSL, curl, libuv, libgit2, libarchive, Open vSwitch, tcpdump, tmux and zstd.

Contract, task-based work paid at $130 per approved task, performed remotely in Mercor Studio.

2. Key Responsibilities

• Select tasks from a pre-validated pool of C repositories, each pinned to a specific git commit and arriving with an engineering question, positive and negative rubrics, foils, and a golden solution

• Explore the repository until you genuinely understand the subsystem in question, including the relevant PR or issue history

• Rewrite the task's question so it defeats frontier coding agents while remaining well-defined and fairly answerable

• Adjust rubrics and foils so they reward correct reasoning and reject plausible-but-wrong answers

• Run the full validation loop in Studio — Check, Golden, Run, Analyze — and iterate until every stage passes

• Document your work in the task README and submit for expert review, addressing reviewer feedback on returned tasks

3. Ideal Qualifications

• 3+ years of professional software engineering experience, with substantial production C

• Demonstrated ability to navigate a large, unfamiliar C codebase and explain how it behaves at runtime — not just what the source says

• Comfort with the things that make C systems hard to read: preprocessor-heavy builds, platform conditionals, manual memory management, and autotools/CMake/Meson build graphs

• Experience with databases, cryptography, networking protocols, or systems programming is highly relevant — the task mix is weighted toward architecture and system design (39%) and code onboarding (34%), with a meaningful security slice

• Ability to use debuggers, sanitizers, tracing, and profilers to establish what the code actually does

• Precise written English: the questions and rubrics you write are the product

4. Working Details

• Fully remote and asynchronous, with expert team leads across US, India, and Nigeria time zones

• Work is performed in Mercor Studio; time is tracked with Insightful, and platform access is provisioned through Okta

• Onboarding requires identity verification, a background check, signed Terms of Work and CIIAA, a tax form, and passing a short calibration quiz before task access is granted

• Payment is per approved task; every task is reviewed by a second engineer and a super reviewer before acceptance

5. Application Process

• Submit your resume or relevant technical background to get started

• Qualified applicants may be asked to complete a brief technical assessment or provide additional information