OpenAI Codex is a standalone AI coding application that serves as a command center for managing multiple AI coding agents simultaneously. Launched on February 2, 2026 for macOS and expanded to Windows on March 4, 2026, Codex enables developers to run parallel coding tasks across projects using built-in worktrees and cloud environments. The app features a multi-agent architecture where each agent operates in separate threads organized by project, allowing seamless context switching without losing progress. Codex includes an Automations system that runs agents on user-defined schedules in the background, combining instructions with optional Skills to handle recurring tasks like code review, documentation, and prototyping. The Skills system extends Codex beyond code generation to handle code understanding, testing, and documentation aligned with team standards. Codex supports multimodal inputs including screenshots for UI/UX refinement, enabling developers to convert wireframes into functional applications. Agent Personalities allow users to customize the AI's communication style from pragmatic to empathetic. Powered by GPT-5.3-Codex and the codex-mini model, the app integrates with existing IDEs and supports the full ChatGPT ecosystem. As of early March 2026, Codex has reached 2 million weekly active users with 25% week-over-week growth.