🦀 55,000 Lines of Rust Written by LLMs in 5 Weeks#
A project that would have taken 5 years was completed in 5 weeks of evenings and weekends. The cost? ~£40 in tokens. 🤯
📖 The Project: rars#
rars is a complete RAR implementation in Rust — a compressor supporting all versions of the RAR format, from the original DOS version to RAR5.
Nobody had done it before because it would have taken ~5 years of engineering. With LLMs, it took 5 weeks.
🤖 Tools Used#
- OpenAI Codex 5.5 + Claude Opus 4.7
- ~£40 in (heavily subsidized) tokens
- 55,000 lines of generated code
- Almost earned the author an OpenAI ban 🫠
📊 Honest Results#
“Yes, it’s 55k lines of slop. No, it’s not that fast. But it works.”
🎯 The Most Important Lesson#
The author isn’t a beginner — they have other complex reverse-engineering projects. LLMs didn’t replace their expertise; they multiplied it. The difference between a developer with LLMs and one without isn’t speed: it’s which projects become possible.
💡 Explanation in a nutshell#
rars is an open-source Rust library implementing the complete RAR format (compression + decompression for all versions), built in ~5 weeks using LLMs (OpenAI Codex + Claude) for about £40 in tokens. It demonstrates that LLMs enable reverse-engineering projects that would previously be economically unviable for an individual developer.
More information at the link 👇
