What is Codex?
Codex's Top Features
Key capabilities that make Codex stand out.
Automated code generation and modification from natural language prompts
Code understanding and codebase Q&A
Cloud and local execution with stateful handoff between environments
Parallel and proactive task handling in isolated sandboxes
Automated pull request reviews with runnable validation and suggestions
IDE and CLI integration, including a VS Code extension
Secure authentication with multi‑factor support
Pull request creation and proposal automation
Reinforcement learning on real‑world codebases for iterative, instruction‑following behavior
Seamless GitHub repository integration for continuous delivery and faster iteration
Use Cases
Who benefits most from this tool.
Backend engineer
Generate REST endpoints, write unit tests, and fix failing integrations from natural language specs.
Frontend developer
Implement UI components and state management, and modify existing code based on product requirements.
Full‑stack team
Scaffold new projects, configure routing and data models, and set up CI with iterative testing.
Data scientist
Translate exploratory notebooks into production pipelines and optimize performance bottlenecks.
QA engineer
Auto-generate unit, integration, and regression tests and triage failures with explanations.
DevOps engineer
Author CLI scripts and GitHub Actions, validate builds, and automate deployment steps.
Tech lead / Reviewer
Run automated pull request reviews, reason across dependencies, and suggest improvements in PRs.
Project maintainer
Refactor legacy modules safely, rename symbols at scale, and keep style consistent across the codebase.
New team member
Ask questions about the codebase to accelerate onboarding and clarify unfamiliar sections.
Open‑source contributor
Propose and create pull requests directly from issues and natural language prompts.
Tags
AIcodingcloud-basedproduction-ready codecode reviewsIDEsCLIsGitHubdeveloper productivitymultiple programming languages
Codex's Pricing
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OpenAIai lab
Creating safe AGI that benefits all of humanity
426 Tools6 ModelsFounded 2015San Francisco, CA
View full profileTools by OpenAI
Other AI tools from the same organization.
AI Models by OpenAI
Large language models from the same organization.
| Model | Context Window | Price (In / Out per M) |
|---|---|---|
| GPT-5.5Current | 1.1M | $5.00 / $30.00 |
| GPT-5.5 ProCurrent | 1.1M | $30.00 / $180.00 |
| GPT-5.4 MiniCurrent | 400K | $0.75 / $4.50 |
| GPT-5.4 NanoCurrent | 400K | $0.20 / $1.25 |
| GPT-5.4Current | 1.1M | $2.50 / $15.00 |
| GPT-5.4 ProCurrent | 1.1M | $30.00 / $180.00 |
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Resources & Guides
Tutorials, guides, and in-depth resources.
OpenAI Codex Quick Start Guide
quickstartGet Codex running in under 5 minutes. Covers CLI installation on every platform, authentication with ChatGPT or API keys, your first tasks, the desktop app, Codex Cloud, and IDE extensions.
Codex CLI: The Complete Guide
guideMaster Codex CLI: interactive vs exec mode, key flags (--full-auto, --sandbox, --model), config.toml setup, slash commands, and remote WebSocket sessions.
Mastering AGENTS.md: Codex Custom Instructions
guideComplete guide to AGENTS.md for OpenAI Codex — discovery hierarchy, override files, fallback filenames, /init scaffold, size limits, verification, and troubleshooting.
Codex Skills & Plugins: Extend Your Agent
guideA comprehensive guide to the Codex Skills and Plugins system - how skills are defined, stored, invoked, bundled into plugins, and configured for OpenAI agents.
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User Reviews
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Frequently Asked Questions
What is OpenAI Codex?
OpenAI Codex is a cloud-based software engineering agent that can write features, fix bugs, answer questions about your codebase, and propose pull requests from natural language prompts.
Who can access OpenAI Codex?
Codex is available to ChatGPT Pro, Business, and Enterprise users, and is being rolled out to Plus and Edu users.
What programming languages does Codex support?
Codex supports a wide range of popular programming languages, frameworks, and libraries, enabling code generation, refactoring, and understanding across multiple stacks.
How does Codex write and review code?
Powered by the codex-1 model optimized for software engineering and trained via reinforcement learning on real-world tasks, Codex can work in parallel and iteratively test code until it meets specified criteria.
Can Codex help with debugging or optimizing code?
Yes. Codex can fix bugs, explain complex logic, and refactor and optimize code to improve efficiency and maintainability while preserving intended behavior.
Is Codex available in my preferred development environment?
Yes. Codex integrates via a CLI and a VS Code extension and can also be used from an IDE terminal, making it compatible with many development setups.
Does OpenAI use my code or prompts submitted to Codex for model training?
For Business, Enterprise, and Edu users, OpenAI does not use inputs or outputs from Codex by default to improve models. Pro and Plus users can disable training in ChatGPT data controls.
Can Codex automate repetitive engineering tasks?
Yes. Codex can automate tasks such as writing tests, renaming, refactoring, and scaffolding projects so developers can focus on higher‑value work.
What are the “Insert” and “Edit” capabilities of Codex?
Insert and Edit let you add contextually relevant text within existing code or modify code based on instructions, making updates and refactors efficient.
How do I get started with Codex?
Review the Codex Overview documentation, explore best practices, and use the built‑in guides to integrate Codex for code generation, understanding, and optimization.