hax: A Minimalist C-Based Coding Agent That Lives in Your Terminal
Hax – a minimalist, terminal-native coding agent written in C
hax is a single native C binary that starts instantly and uses only a few MB of RAM, leaving more memory for local LLMs. It auto-discovers model and runtime capabilities, supports OpenAI, Anthropic, Codex, OpenRouter, and llama.cpp, and respects your terminal by streaming Markdown and tool output without messing with scrollback. With XDG paths, plain-text configs, and subprocess composition, it's a well-behaved Unix tool for developers who want an inspectable, resource-conscious agent.
If you want MCP marketplaces, a plugin runtime, IDE panels, or per-command permission prompts, other agents build exactly that — hax deliberately doesn't, and docs/philosophy.md explains each omission and the pattern that covers the need.
- losvedir
Something about having a very fast, very small harness written in C only to drive LLMs amuses me. Like putting a big ass spoiler on a minivan or something.
- mark_l_watson
I didn't try Hax but I hope someone who has can answer a question: does it support suspending current operation if user hits ESC key?
EDIT: I just looked at interrupt.c in the github repo: handles user interrupts. I trashed my Common Lisp harness because I had problems handling interrupts in a portable way. I did better with Racket. I am traveling on vacation without a computer, will try Hax when I get home.
- abawany
I just installed it via homebrew on macos and used the anthropic-compatible custom provider option to configure it to use with deepseek-flash and then used this setup to build a quick rust project that I had been deferring for months - total cost: 1 us cent and under 10 minutes total for setup and etc. Thank you for making such a lean and clean option.
- Bleaphar
Would love to hear more about the decision to create the terminal in C? Also what did you use to record your demo video? It looks awesome!
- all2
Note to be confused with Haxe: https://haxe.org/