What is Codex CLI used for?

Codex CLI is OpenAI's open-source coding agent for the terminal, written in Rust, which can sign in with a ChatGPT plan or use an API key. It is a good fit for terminal-first AI-assisted coding and delegating code changes from the command line.

Is Codex CLI open source?

Yes. Codex CLI is open source under the Apache-2.0 licence. Its source code is on GitHub at openai/codex and is written mainly in Rust.

Yes. Codex CLI is open source, so the software itself is free to use. A managed cloud version is also available.

What is Codex CLI an alternative to?

Codex CLI is an open-source alternative to Claude Code, GitHub Copilot, Cursor and Devin. Other open-source alternatives to Claude Code include OpenCode, Kilo Code and Cline.

Is Codex CLI actively maintained?

Yes. The most recent commit to Codex CLI was on 2 October 2026. The project has 128k stars on GitHub.

Codex CLI: open-source alternative to Claude Code

About Codex CLI

Codex CLI is OpenAI's coding agent, and it runs locally in your terminal. It is open source under the Apache-2.0 license and written in Rust. Developers start it by running the codex command and then ask it to read, explain and change the code in their project.

It is installed through standalone scripts for Mac, Linux and Windows, through package managers, or by downloading a binary for your platform from GitHub Releases. You can sign in with a ChatGPT account to use it as part of a Plus, Pro, Business, Edu or Enterprise plan, or authenticate with an API key instead.

The README distinguishes the CLI from other Codex surfaces: an IDE extension for VS Code, Cursor and Windsurf, a desktop app launched with codex app, and the cloud-based Codex Web at chatgpt.com/codex. The CLI suits developers who prefer to stay in the terminal and want an agent whose client code is open.

Key features

Terminal-based coding agent that runs locally
Sign in with a ChatGPT plan or API key
Installers for Mac, Linux and Windows
Standalone binaries on GitHub Releases
Related IDE extension and desktop app
Open-source Rust codebase under Apache-2.0

Good fit for

→Terminal-first AI-assisted coding
→Delegating code changes from the command line

Built with: Rust
Tags: coding-agent; cli; ai; openai; terminal; rust; developer-tools; ai-coding

Codex CLI: questions and answers

What is Codex CLI used for?: Codex CLI is OpenAI's open-source coding agent for the terminal, written in Rust, which can sign in with a ChatGPT plan or use an API key. It is a good fit for terminal-first AI-assisted coding and delegating code changes from the command line.
Is Codex CLI open source?: Yes. Codex CLI is open source under the Apache-2.0 licence. Its source code is on GitHub at openai/codex and is written mainly in Rust.
Is Codex CLI free?: Yes. Codex CLI is open source, so the software itself is free to use. A managed cloud version is also available.
What is Codex CLI an alternative to?: Codex CLI is an open-source alternative to Claude Code, GitHub Copilot, Cursor and Devin. Other open-source alternatives to Claude Code include OpenCode, Kilo Code and Cline.
Is Codex CLI actively maintained?: Yes. The most recent commit to Codex CLI was on 2 October 2026. The project has 128k stars on GitHub.