Codex

Codex is an AI coding agent from OpenAI for software engineering work across codebases, repositories, and development environments. It can take on tasks such as building features, fixing bugs, writing tests, reviewing pull requests, refactoring code, and handling migrations. Codex is designed for end to end engineering work rather than only answering coding questions, with agents able to work through tasks and produce changes for review. Developers can use Codex through ChatGPT, the Codex app, editor integrations, and the terminal. It supports workflows where an agent investigates a repository, makes changes, runs relevant checks, and prepares work for a developer to review. Codex also supports parallel agent workflows, cloud environments, worktrees, reusable Skills, and scheduled background work for tasks such as issue triage, monitoring, and other recurring engineering jobs. Codex stands out through its combination of agentic coding, multiple execution environments, parallel work, and workflow customization. OpenAI describes it as a command center for agentic coding, while its documentation covers coding tasks, code review, security, usage limits, and credit based pricing. Codex usage is included with eligible ChatGPT plans within plan limits, while additional usage can draw from purchased credits. Buyers should check current model availability, credit rates, plan limits, and whether the workflow needs ChatGPT access or a supported developer setup. For FutureStack, Codex belongs in Coding because its primary buyer intent is AI assisted software engineering. It is best for building features, debugging, refactoring, migrations, code review, test generation, and repeatable agentic development workflows. Developers comparing Codex with Claude Code, Cursor, GitHub Copilot, or other coding agents should compare execution environments, model access, repository workflows, usage limits, and the amount of supervision each workflow requires.