Codex CLI
OpenAI's Apache-2.0 terminal agent, included in the ChatGPT plan you may already pay for.
Codex CLI is OpenAI's coding agent that runs locally on your computer, and unlike Claude Code its client is open source under Apache-2.0. For a subscriber it is the most direct like-for-like swap: sign in with ChatGPT and it draws on your plan (OpenAI's pricing page lists the CLI from Plus at $20/month, with Pro plans at $100, $200 or $500), or use an API key at API rates. It also has a documented local path: pass `--oss` to run against Ollama or LM Studio, and custom OpenAI-compatible providers can be added in its config. The same agent is available as IDE extensions, a desktop app and a cloud agent.
What it does well
- +An open-source client (Apache-2.0) you can read, audit and fork
- +Uses a ChatGPT plan you may already pay for, so there is no second subscription
- +Documented local mode: `--oss` with Ollama or LM Studio, plus custom OpenAI-compatible providers
- +A similar spread of surfaces to Claude Code: terminal, IDE extensions, desktop app and cloud agent
Where it falls short
- −The client is open but the default models and the plan are OpenAI's, so you trade one vendor's subscription tie for another's
- −Codex shares usage with ChatGPT under OpenAI's plan limits, the same shape of constraint as Claude's plans
- −Project instructions live in AGENTS.md, so CLAUDE.md conventions need moving across
- −Local mode is a supported path rather than the tuned experience; expect a capability gap against OpenAI's hosted models
Hardware note
The client is light and runs anywhere a terminal does. Only `--oss` local mode needs serious hardware: the same roughly 24 GB VRAM guidance applies for a 30B-class quantised coding model.
Codex CLI as an alternative to
Where Codex CLI shows up in our comparisons, and how it ranked.
Codex CLI head-to-head
Straight comparisons against the tools people weigh it against.