Last updated 08-14-2026
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Codex
Codex is OpenAI's agentic coding assistant that writes features, fixes bugs, answers codebase questions, and opens pull requests from ChatGPT, a terminal CLI, or an IDE extension. Each cloud task spins up an isolated sandbox preloaded with your GitHub repository, where GPT-5-Codex edits files, runs tests, linters, and type checkers, and commits results you can review or merge. The same ChatGPT account links ChatGPT, the Codex CLI, and the IDE extension so you can pair locally or delegate longer jobs to run in parallel.
Unlike inline autocomplete tools that suggest the next line, Codex treats software engineering as delegated work. You assign a scoped task, wait one to thirty minutes depending on complexity, and get verifiable citations from terminal logs and test output rather than a single pasted snippet. That trade-off favors refactors, test generation, and multi-file features over keystroke-level completion, which is why teams at Ramp, Duolingo, and Harvey use it for PR reviews and background chores they would otherwise postpone.
Developers on ChatGPT Plus, Pro, Business, and Enterprise plans can run Codex in ChatGPT with built-in worktrees, schedule recurring jobs like issue triage or CI monitoring, and teach team standards through Skills. Repositories can include AGENTS.md files that tell Codex how to run tests and follow project conventions. A Codex SDK embeds the same agent in custom workflows, and a Slack integration lets teams assign tasks from channels.
Cloud tasks run in isolated sandboxes preloaded with your GitHub repository
GPT-5-Codex model tuned for agentic coding across CLI, IDE, and cloud environments
Tasks typically finish in 1 to 30 minutes with live progress and terminal log citations
AGENTS.md files guide testing commands and repo conventions inside each sandbox
Codex CLI installs via npm i -g @openai/codex and signs in with your ChatGPT account
codex-mini-latest API priced at $1.50 per 1M input tokens and $6 per 1M output tokens
Slack integration and Codex SDK let teams delegate tasks outside ChatGPT
Delegates multi-file tasks in isolated cloud sandboxes with test and linter execution.
Same ChatGPT login covers ChatGPT, Codex CLI, IDE extension, GitHub, and Slack workflows.
AGENTS.md and Skills let teams encode testing and style rules the agent follows consistently.
Terminal log citations make it easier to audit what the agent changed before merging.
Codex SDK embeds the agent in custom engineering tools with structured outputs.
Cloud tasks take 1 to 30 minutes, slower than interactive inline coding assistants.
Requires a paid ChatGPT Plus, Pro, Business, or Enterprise subscription for product access.
Early builds lack image inputs for frontend work and limited mid-task course correction.
What is Codex from OpenAI?
Codex is OpenAI's agentic coding assistant that writes features, fixes bugs, reviews code, and opens pull requests. It runs in ChatGPT, a terminal CLI, and IDE extensions, with cloud tasks executing inside isolated sandboxes loaded with your repository.
Is Codex included with ChatGPT?
Yes. Codex is available to ChatGPT Plus, Pro, Business, and Enterprise subscribers through ChatGPT, the Codex CLI, and the IDE extension under the same account. Plus and Pro users can also redeem $5 and $50 in free API credits for Codex CLI usage.
How long do Codex cloud tasks take?
Codex cloud tasks typically take between 1 and 30 minutes depending on complexity. You can monitor progress in real time, review terminal citations, request revisions, or open a GitHub pull request when the sandbox commit is ready.
What model powers Codex?
Codex uses GPT-5-Codex, a version of GPT-5 optimized for agentic software engineering. The Codex CLI also supports codex-mini-latest on the Responses API at $1.50 per 1M input tokens and $6 per 1M output tokens with a 75% caching discount.
How does Codex differ from GitHub Copilot?
Codex delegates full tasks in cloud sandboxes that run tests and open pull requests, while Copilot focuses on inline suggestions inside your editor. Codex also connects ChatGPT, CLI, IDE, GitHub, and Slack under one ChatGPT login for parallel agent workflows.
Can Codex read my repository setup instructions?
Yes. Codex reads AGENTS.md files in your repository to learn testing commands, navigation tips, and PR conventions. You can also configure the sandbox environment with setup scripts so dependencies match your real development stack.