Codex
Codex
Codex is OpenAI's coding-focused AI model and CLI tool, included with a ChatGPT Plus subscription ($20/month). It specializes in code auditing, security review, and adversarial testing — the "code surgeon" that catches what code generators miss.
What Codex Is Good At
- Code audits — spotting bugs sitting in production code for weeks unnoticed
- Edge cases — empty input, malformed data, double-clicks, concurrent access
- Race conditions — what breaks when two things happen at the same time
- Security — OWASP top ten, injection attacks, validation gaps, authentication holes
- Long surgical refactors — methodical, focused, won't drift off course
- Adversarial review — playing devil's advocate on a design before it ships
What Codex Is NOT Good At
- Planning architecture — Claude Code's strength
- Writing copy, microcopy, or page text
- Design taste and UI intuition
- Knowing when to stop — the discipline is yours
- Original product strategy
The right frame: Claude plans, designs, and writes. Codex audits and does surgery. They're teammates, not rivals.
The Codex Plugin for Claude Code
Codex integrates directly into Claude Code via an official OpenAI plugin. Available in the Claude Code plugin marketplace, it adds /codex:* slash commands that let you call Codex without leaving the Claude Code window.
Install:
/plugin marketplace add openai/codex-plugin-cc
/plugin install codex@openai-codex
/reload-plugins
/codex:setup
Key commands:
| Command | Purpose |
|---|---|
/codex:review |
Full code audit — bugs, edge cases, security (read-only, not steerable) |
/codex:adversarial-review <focus> |
Stress-test ONE specific concern (steerable, read-only) |
/codex:rescue <task> |
Delegate a fix or investigation (write-capable) |
/codex:setup --enable-review-gate |
Auto-review every time Claude finishes a turn |
/codex:setup --disable-review-gate |
Turn off auto-review |
For the full workflow reference, see the Codex Duo guides in vault.
The Duo Stack
Using Claude Code and Codex together costs $120/month total:
- Claude Max — $100/month (Claude Code with high usage limits)
- ChatGPT Plus — $20/month (Codex + full ChatGPT access)
Two consumer subscriptions. No enterprise contract. No API key billing surprises.
See Also
- Claude Code — Codex's partner in the duo setup
- Master-Agent-Comparison-Matrix — side-by-side comparison of all AI coding agents
- 001-AI-Agents-MOC — full AI agents domain hub