# codex-1

codex-1 is an AI model released by OpenAI on May 16 2025.

## Facts

| Field | Value |
| --- | --- |
| Model | codex-1 |
| Developer | OpenAI |
| Release date | Friday, May 16 2025 |
| Licensing | Closed |

## About codex-1

OpenAI introduced codex-1 in May 2025 to power the Codex cloud agent. Trained from o3 for software engineering, the model could inspect a repository, edit files and run tests in an isolated environment.

Codex users could delegate tasks such as fixing a bug or proposing a patch and review the changes after the agent finished. OpenAI evaluated the shipping configuration at medium reasoning effort.

## Questions and answers

### When was codex-1 released?

codex-1 was released by OpenAI on Friday, May 16 2025.

### Who made codex-1?

codex-1 was built by OpenAI. Creators of ChatGPT and the GPT series of models. Pioneered large-scale language model research.

### Is codex-1 open source?

No. codex-1 is a closed model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.

### What came before and after codex-1?

OpenAI's previous tracked release was o4-mini-high on Apr 16 2025, 30 days earlier. It was followed by codex-mini-latest on May 16 2025.


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Canonical page: https://aireleasetracker.com/model/openai/codex-1
Site index: https://aireleasetracker.com/llms.txt
Source: AI Release Tracker (https://aireleasetracker.com). Most benchmark scores come from lab launch material; gathered results identify the leaderboard that published them.