Codex
OpenAI Codex Harness Is Open Source: Build Agents Into Your Own App
OpenAI's Codex platform post explains how the open-source harness, SDK and app-server let products keep their own interface, context, tools and approval rules.
Closed Source model
GPT-5
OpenAI’s proprietary frontier GPT family for general reasoning, coding and multimodal work.
- Organization
- OpenAI
- Official source
- Visit source ↗
- Last checked
- July 27, 2026
- License
- Proprietary API