# Source: https://developers.openai.com/changelog/codex/2025-11-18.md

# Introducing GPT-5.1-Codex-Max

- Date: 2025-11-18
- Products: Codex

[Today we are releasing GPT-5.1-Codex-Max](http://www.openai.com/index/gpt-5-1-codex-max), our new frontier agentic coding model.

GPT‑5.1-Codex-Max is built on an update to our foundational reasoning model, which is trained on agentic tasks across software engineering, math, research, and more. GPT‑5.1-Codex-Max is faster, more intelligent, and more token-efficient at every stage of the development cycle–and a new step towards becoming a reliable coding partner.

Starting today, the CLI and IDE Extension will default to `gpt-5.1-codex-max` for users that are signed in with ChatGPT. API access for the model will come soon.

For non-latency-sensitive tasks, we’ve also added a new Extra High (`xhigh`) reasoning effort, which lets the model think for an even longer period of time for a better answer. We still recommend medium as your daily driver for most tasks.

If you have a model specified in your [`config.toml` configuration file](https://developers.openai.com/codex/local-config), you can instead try out `gpt-5.1-codex-max` for a new Codex CLI session using:

```bash
codex --model gpt-5.1-codex-max
```

You can also use the `/model` slash command in the CLI. In the Codex IDE Extension you can select GPT-5.1-Codex from the dropdown menu.

If you want to switch for all sessions, you can change your default model to `gpt-5.1-codex-max` by updating your `config.toml` [configuration file](https://developers.openai.com/codex/local-config):

```toml
model = "gpt-5.1-codex-max”
```