GPT-5-Codex Now Available to Developers via Codex API Key

OpenAI now offers GPT-5-Codex to developers via Codex API keys, at the same price as GPT-5 and available only through the Responses API. This enables IDE/editor integrations—see platform docs and changelog.

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GPT-5-Codex Now Available to Developers via Codex API Key

TL;DR

  • Responses API only: GPT‑5‑Codex now accessible with a Codex API key (in addition to ChatGPT subscriptions); interactions must be routed through the Responses API.
  • Pricing parity: GPT‑5‑Codex priced the same as GPT‑5.
  • Model snapshot to be regularly updated.
  • Enables embedding into IDE plugins and editor extensions (examples: Cline, Roo, Kilo, Cursor) for agentic coding inside existing workflows.

Update: GPT‑5‑Codex now available via Codex API key (Sept 23, 2025)

OpenAI added a brief update on September 23, 2025 announcing that GPT‑5‑Codex is now available to developers using a Codex API key, in addition to access through ChatGPT subscriptions. The update clarifies pricing and API access and points to developer resources for implementation details.

What changed

  • API availability: GPT‑5‑Codex can be accessed with a Codex API key, not only through ChatGPT subscriptions.
  • Pricing parity: GPT‑5‑Codex is available at the same price as GPT‑5.
  • API surface: The model is available in the Responses API only.
  • Model updates: The underlying model snapshot will be regularly updated.

The announcement links to the model documentation at the OpenAI platform docs and to the Codex changelog for technical details and ongoing updates: the developer documentation is available at http://platform.openai.com/docs/models/gpt-5-codex and the changelog at https://developers.openai.com/codex/changelog.

What this enables for tooling and editors

Making GPT‑5‑Codex accessible via an API key opens the door for deeper integration into third‑party developer tooling and editor extensions. This update enables the model to be embedded into IDE plugins and external extensions—examples noted include integrations such as Cline/Roo/Kilo and Cursor, among others—so that agentic coding features can run directly inside familiar workflows and editors via the Responses API.

Because access is provided through an API key and priced on parity with GPT‑5, teams building editor extensions or developer tools can evaluate the integration path and cost against existing GPT‑5 usage. The Responses API constraint means integrations must route interactions through that API surface.

Where to read more

Full technical details and future changelog entries are available in the official docs and changelog:

Original announcement: https://openai.com/index/introducing-upgrades-to-codex/

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