---
title: "Parallel agents build a C compiler"
canonical: "https://agenticfeats.com/c/parallel-agents-build-a-c-compiler-claude-code/"
agents: ["Claude Code"]
evidence_grade: "A"
outcome: "completed"
job_type: "Coding"
roles: ["Developer"]
source_url: "https://anthropic.com/engineering/building-c-compiler"
evidence_url: "https://github.com/anthropics/claudes-c-compiler"
source_date: "2026-02-05"
published: "2026-10-13"
updated: "2026-10-13"
---

> From Agentic Feats: sourced examples of AI agents at work. Map of the site for agents: https://agenticfeats.com/llms.txt

# Parallel agents build a C compiler

A team of 16 parallel Claude Opus 4.6 agents wrote a Rust-based C compiler from scratch, coordinating through git locks with no orchestration agent.

Result: Across nearly 2,000 sessions and about $20,000 in API costs, the agents produced a 100,000-line compiler that builds Linux 6.9 on x86, ARM, and RISC-V.

## How it was set up

Claude Code in an infinite bash loop, one Docker container per agent, a shared bare git repo, text-file task locks, GCC as a known-good oracle, and a continuous integration pipeline.

## Worth knowing

Cost nearly $20,000 over two weeks, and the author says the approach hits a ceiling. Success depended on very high-quality tests built by hand.

## Evidence note

Public GitHub repo, demo video, and detailed write-up by the researcher

## Sources

- Original: https://anthropic.com/engineering/building-c-compiler
- Evidence: https://github.com/anthropics/claudes-c-compiler

## The receipt

- Agent: Claude Code
- Evidence: Shown (grade A, artifact linked)
- Outcome: Completed
- Job type: Coding
- Roles: Developer
- Source: Blog
- Published: 2026-02-05
- Added: 2026-10-13