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OpenAI Codex
OpenAI's coding agent, in ChatGPT and the terminal. AI model and agent, with a free plan; runs on desktop, web. The stack builder picks it for AI coding.
What it is known for
- Strengths: code generation and GitHub code review; computer use and browser automation; scheduled tasks and MCP server connections.
- For: developers and technical teams, students, open source contributors, enterprises.
- Runs on: ChatGPT web, macOS and Windows desktop apps, iOS, terminal CLI, IDE extension, cloud.
- Learning curve: the page does not say.
- Works with: GitHub, GitLab (beta), Slack, Linear, VS Code extension and MCP servers.
Read on October 9, 2026 from learn.chatgpt.com/docs, learn.chatgpt.com/docs/pricing.
Plans and prices
| Plan | Price | What you get |
|---|---|---|
| ChatGPT Free | Free | Codex included, lowest limits |
| ChatGPT Plus | $20/mo | Codex included; per-5-hour message limits by model |
| ChatGPT Pro | $100/mo | From $100 ($200/$500 options); no five-hour limit |
| ChatGPT Business | $25/mo | Per user, 2+ users; Plus-level Codex limits |
Checked by hand against learn.chatgpt.com/docs/pricing on October 6, 2026; confidence high. Prices are monthly in US dollars unless the row says otherwise; the builder counts the plan it starts on, ChatGPT Plus.
When the stack builder picks it
The builder reads each job's rules from the top and takes the first step whose conditions hold and whose plan fits the money left. OpenAI Codex is named in these steps:
- AI coding, step 4 of 4, otherwise: ChatGPT Plus ($20/mo); the step also names Claude Code, Cursor, Devin, Kiro and Augment Code, and the best score takes it.
The rules are public in stack-rules.json, and how the stack builder scores explains the tie-break.
Works with
Godot, Unity and Unreal Engine.
Alternatives the same rules name
- Claude Code: Anthropic's coding agent that works in your terminal and editor. From $20/mo.
- Cursor: Code editor with an AI agent that edits your whole project. From free.
- Devin: Cognition’s cloud coding agent, with the Windsurf IDE on the desktop. From free.
- Kiro: AWS’s spec-driven agentic IDE. From free.
- Augment Code: A context-engine coding agent for large codebases. From $20/mo.
Signals and what people say
- Hacker News, 30 days to October 15, 2026: 4 stories
Change log
- October 6, 2026: plans and prices first recorded from learn.chatgpt.com/docs/pricing.
Logo: Nameryn monogram (no free mark on file), CC0 1.0.