Recommended models
Flagship frontier model for professional work that brings the industry-leading coding capabilities of GPT-5.3-Codex together with stronger reasoning, tool use, and agentic workflows.
Fast, efficient mini model for responsive coding tasks and subagents.
Industry-leading coding model for complex software engineering. Its coding capabilities now also power GPT-5.4.
Text-only research preview model optimized for near-instant, real-time coding iteration. Available to ChatGPT Pro users.
For most tasks in Codex, start with gpt-5.4. It combines strong coding,
reasoning, native computer use, and broader professional workflows in one
model. 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.
Alternative models
Advanced coding model for real-world engineering. Succeeded by GPT-5.3-Codex.
Previous general-purpose model for coding and agentic tasks across industries and domains. Succeeded by GPT-5.4.
Optimized for long-horizon, agentic coding tasks in Codex.
Great for coding and agentic tasks across domains. Succeeded by GPT-5.2.
Optimized for long-running, agentic coding tasks in Codex. Succeeded by GPT-5.1-Codex-Max.
Version of GPT-5 tuned for long-running, agentic coding tasks. Succeeded by GPT-5.1-Codex.
Smaller, more cost-effective version of GPT-5-Codex. Succeeded by GPT-5.1-Codex-Mini.
Reasoning model for coding and agentic tasks across domains. Succeeded by GPT-5.1.
Other models
Codex works best with the 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.
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-5.4"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-5.4Choosing your model for cloud tasks
Currently, you can’t change the default model for Codex cloud tasks.