Models – Codex
Recommended models
gpt-5.5
OpenAI's newest frontier model for complex coding, computer use, knowledge work, and research workflows in Codex.
codex -m gpt-5.5
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Capability
Speed
Codex CLI & SDK
Codex app & IDE extension
Codex Cloud
ChatGPT Credits
API Access
gpt-5.4
Flagship frontier model for professional work with strong coding, reasoning, tool use, and agentic workflow capabilities.
codex -m gpt-5.4
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Capability
Speed
Codex CLI & SDK
Codex app & IDE extension
Codex Cloud
ChatGPT Credits
API Access
gpt-5.4-mini
Fast, efficient mini model for responsive coding tasks and subagents.
codex -m gpt-5.4-mini
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Capability
Speed
Codex CLI & SDK
Codex app & IDE extension
Codex Cloud
ChatGPT Credits
API Access
gpt-5.3-codex-spark
Text-only research preview model optimized for near-instant, real-time coding iteration. Available to ChatGPT Pro users.
codex -m gpt-5.3-codex-spark
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Capability
Speed
Codex CLI & SDK
Codex app & IDE extension
Codex Cloud
ChatGPT Credits
API Access
For most tasks in Codex, start with
gpt-5.5. It is
strongest for complex coding, computer use, knowledge work, and research
workflows. GPT-5.5 is currently available in Codex when you sign in with
ChatGPT or API-key authentication. Use
gpt-5.4-mini
when you want a faster, lower-cost option for lighter coding tasks or
subagents. The gpt-5.3-codex-spark model is available in research preview
for ChatGPT Pro subscribers and is optimized for near-instant, real-time
coding iteration.
Other models
When you sign in with ChatGPT, Codex works best with the recommended models listed above.
You can also point Codex at any model and provider that supports either the Chat Completions or Responses APIs to fit your specific use case.
Support for the Chat Completions API is deprecated and will be removed in future releases of Codex.
Deprecated Codex models
The gpt-5.2 and gpt-5.3-codex models are deprecated in Codex when you sign in with ChatGPT. If your scripts, configuration files, or codex exec --model commands still reference deprecated models, update them to the latest model listed above.
Some models that are deprecated for ChatGPT sign-in may still be available in the API. If your workflow depends on one of those models, use API-key authentication and check the API models page for current availability.
Configuring models
Configure your default local model
The Codex CLI and IDE extension use the same config.toml configuration file. To specify a model, add a model entry to your configuration file. If you don’t specify a model, the Codex app, CLI, or IDE Extension defaults to a recommended model.
model = "gpt-5.5"
Choosing a different local model temporarily
In the Codex CLI, you can use the /model command during an active thread to change the model. In the IDE extension, you can use the model selector below the input box to choose your model.
To start a new Codex CLI thread with a specific model or to specify the model for codex exec you can use the --model/-m flag:
codex -m gpt-5.5
Choosing your model for cloud tasks
Currently, you can’t change the default model for Codex cloud tasks.