OpenAI's cloud software-engineering agent (2025 reboot)
Codex is OpenAI's cloud-based software engineering agent — relaunched in 2025 around GPT-5-Codex. It runs in a sandboxed environment, can write code, run tests, and propose pull requests. Available inside ChatGPT, in a CLI, and via the OpenAI API.
OpenAI's reboot of the original Codex brand — now a cloud agent powered by GPT-5-Codex, accessible in ChatGPT, via CLI, and via API.
If you're already a ChatGPT subscriber, Codex is free to try and surprisingly capable. If coding is your main workflow, Claude Code or Cursor will likely serve you better.
| Plan | Price | What you get |
|---|---|---|
| ChatGPT Plus | $20 per month |
|
| ChatGPT Pro | $200 per month |
|
Pricing last verified May 1, 2026
Codex is the right agent if you already pay for ChatGPT and want to extend it into engineering work. For dedicated coding workflows, Claude Code is more loved and Cursor is more polished — but Codex being free with Plus makes it a strong "try before paying for anything else" option.