OpenAI open-sources the Codex harness

OpenAI announced at DevDay that it has open-sourced the Codex agent's harness, letting developers inspect, modify, and self-host the coding agent runtime, which is also integrated into its cloud offering.

2026-09-30 ~ 2026-09-30 · 4 related posts

• OpenAI open-sources Codex Harness for building coding agents — HarperSCarroll · 2026-09-30
• OpenAI Codex harness is now open source — BorisMPower · 2026-09-30
• OpenAI open-sources its Codex agent harness, now available in the cloud — YashasGunderia · 2026-09-30

1 near-duplicate retellings: talkaboutdesign