Codex is an AI system by OpenAI that can understand and generate computer code. It's designed to assist programmers by writing code, suggesting changes, explaining existing code, and helping to fix bugs. Codex supports many programming languages and acts as a smart assistant for developers, enabling them to describe what they want, and Codex generates the corresponding code. OpenAI has integrated code-focused capabilities into its GPT models, so there is no separate "Codex" button in the current ChatGPT.
The latest version, GPT-5.3-Codex, is available through any paid ChatGPT plan. It can be accessed via the Codex app (macOS only), CLI, IDE extension, and web interface. OpenAI is also planning to enable API access soon. Key features include enhanced agentic capabilities for complex tasks, interactive collaboration, and advanced cybersecurity measures. The Codex app is designed for multi-agent workflows and allows users to run multiple AI agents simultaneously to handle tasks like bug hunting, feature writing, and testing in the background. It also offers cloud execution, allowing tasks to run in isolated cloud containers.
Codex is available to users with ChatGPT Plus, Pro, Business, Enterprise, or EDU plans. The pricing depends on the subscription tier and usage patterns, as Codex is integrated into existing ChatGPT subscription plans. For example, the Plus plan is priced at $20 per month. OpenAI has also made Codex accessible for ChatGPT Free and Go users for a limited promotional period. However, it's expected that the free tiers will face some throttling soon to manage costs.