codex

OpenAI Codex CLI brings AI-assisted software development to the Linux terminal. Start it in a project directory to explore an unfamiliar codebase, ask for an implementation plan, make changes across files, run local development tools, or review a patch. Codex works against the repository on your computer, so you can follow its commands and inspect its changes in the same workflow you already use for development.

Main features

• Work in a local repository: Ask Codex to explain code, trace a bug, plan a feature, or edit project files from the terminal.
• Choose how much control to give it: Select a model and reasoning effort, configure permissions, and decide when Codex can run commands or change files.
• Review code changes: Request a review of uncommitted changes, a commit, or a base branch. Codex reports findings without modifying the working tree during the review.
• Automate repeatable tasks: Use codex exec in scripts and CI workflows as well as interactive sessions.
• Add project instructions and tools: Use AGENTS.md files, skills, and plugins to give Codex reusable guidance or connect it to developer tools.
• Provide visual context: Include screenshots or diagrams when a coding task depends on a visible interface or design.

The command-line program runs locally, but model use requires a configured account or provider; Codex CLI is not an offline local-model runner. OpenAI offers sign-in through a ChatGPT account or API-key setup.

Models

ChatGPT is a broader conversational assistant for tasks such as writing, research, file analysis, and general coding help. Codex CLI is narrower: it is built to work directly with a project’s files, commands, and diffs.

Things to consider

Codex CLI is aimed at developers comfortable working in a terminal and reviewing AI-generated changes. Model access and usage depend on the connected account or provider.

Codex CLI is a strong fit for Linux developers who want an AI agent in their repository and prefer to steer its work through terminal permissions and code review. Choose a provider-flexible tool such as OpenCode when switching among Claude, OpenAI, local, and other models matters more than using Codex’s workflow.