MicroCodex - Ultra-lightweight coding agent in C++

Show HN: MicroCodex Coding Agent – OpenAI/codex reimplemented in C++ <1MB binary

MicroCodex - Ultra-lightweight coding agent in C++

MicroCodex is an ultra-lightweight coding agent that runs locally in your terminal. Written in C++23, it delivers a binary under 1MB, making it incredibly fast and resource-efficient. It offers one-shot prompts, an interactive terminal UI, local coding tools, durable conversations, and automatic context compaction. You can use it with your ChatGPT plan, and it supports Codex skills. Installation is a simple curl command on Mac or Linux. Experience a coding agent that's both powerful and minimal.

MicroCodex is an ultra-lightweight coding agent that runs locally in your terminal, written in C++23, with a binary under 1MB.
  1. fractorial

    I’m not quite sure why the harness itself needs to be small. Isn’t the system prompt and management of system prompt the bit you want lightweight?

  2. orliesaurus

    i love the idea, but you also need to maintain it long term: in today's world what is the best practice to do that... do you spin up an agent anytime codex-cli updates and mirror the updates in c++ and push a new release? or idk... set up an automated process that does this on a worker on CF in a sandbox when npm updates @openai/codex?

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2026-08-02