Codex
Codex is OpenAI's coding agent. It writes and reviews code from ChatGPT, the terminal, or an IDE, and it can keep working in the cloud.
Tags
- coding agent
- pull requests
- cloud
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What people actually do with this tool
Public posts. The line is a short account of the source, and the link goes to that post.
Sankalp used Codex in GPU Mode's auto-research contest to speed a batched QR kernel to 232x the baseline and finished 12th of 183.
Simon Willison ported the JustHTML HTML5 parser from Python to dependency-free JavaScript with Codex CLI and GPT-5.2 in about 4.5 hours.
Prompt they used
We are going to create a JavaScript port of ~/dev/justhtml - an HTML parsing library that passes the full ~/dev/html5lib-tests test suite. It is going to have a similar API to the Python library but in JavaScript. It will have no dependencies other than raw JavaScript, hence it will work great in the browser and node.js and other environments. Start by reading ~/dev/justhtml and designing the user-facing API for the new library - create a spec.md containing your plan.
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