Codex
Release date unpublished
OpenAI's coding agent, available as the open-source Codex CLI, an IDE extension, a desktop app and Codex Cloud on the web.
- Interface
- CLI, IDE, DESKTOP, WEB
- Pricing
- Subscription
- Models
- Vendor's own models
- Best Terminal-Bench
- 58.18% (v4.0) · GPT-6 Astra
- Open source
- Yes
- Licence
- Apache License 2.0
Terminal-Benchv4.0 · per harness + model pairing
| GPT-6 Astra | 58.18% |
| GPT-6.1 Sol | 58.18% |
| GPT-6 Sol | 49.39% |
| GPT-5.6 Sol | 37.27% |
| GPT-5.6 Terra | 21.52% |
| GPT-5.6 Luna | 17.27% |
| GPT-6 Luna | 16.36% |
Strengths & weaknesses
Strengths
- #3 on Terminal-Bench 4.0 (GPT-6 Astra and GPT-6.1 Sol, both 58.2%)
- CLI is open source (Apache-2.0)
- Included in every ChatGPT plan from Free upward
- Custom providers via any Responses-API-compatible gateway, incl. Amazon Bedrock
Weaknesses
- Custom providers must expose a Responses API endpoint; Chat Completions-only endpoints are unsupported
- Free and Go plans limited to lighter use on GPT-6 Luna
Notable: appears on the official Terminal-Bench leaderboard (tbench.ai, Terminal-Bench 4.0 — the only version tbench.ai currently shows), best rank #3; only five distinct agents are listed there, so every one is top-10. Scores are TB 4.0 resolution rates (best per model across reasoning efforts), fetched 2026-10-14 — not comparable with older Terminal-Bench 2.x figures. releaseDate null: Codex CLI launched 2025-04-16 per launch coverage (TechCrunch) and the GitHub repo was created 2025-04-13, but no OpenAI page confirming the date could be fetched (openai.com returned 403). Open source applies to the CLI; the app and cloud are proprietary.