OpenAI · Coding agent (desktop app, CLI, IDE extension, web, iOS)

OpenAI Codex

OpenAI's coding agent, included with ChatGPT plans and usable with an API key.

AI Coding Assistants AI Agents & Frameworks

Provider: OpenAI
Latest confirmed model: GPT-6.1 Sol (Sep 29, 2026)
Pricing: Free plan + paid
Free plan: Yes
API: Yes
Status: Generally available
Last verified: Oct 19, 2026

Visit official website Pricing page API docs

What is OpenAI Codex?

Codex is OpenAI's software engineering agent that can write, edit and review code locally or run tasks in the cloud. It is available in a desktop app, a command-line tool, an IDE extension, on the web and on iOS, depending on the plan. Usage comes from a ChatGPT subscription, or from an API key billed at token rates.

Engineering backlogs contain many well-defined coding tasks. Codex takes those tasks on so developers can focus on review and design.

Why use OpenAI Codex?

Practical benefits

Included in every ChatGPT plan including Free
Local and cloud task modes
Choice of GPT-6 family models
API-key option for CLI, SDK and IDE

Who it suits

ChatGPT subscribers who code
Developers wanting a terminal agent
Teams on ChatGPT Business or Enterprise

When another tool may fit better

Users needing cloud tasks via API key only (cloud features need ChatGPT sign-in)
Heavy users on Free or Go tiers

Learning curve: Some experience helps
Skills needed: Programming knowledge and ability to review diffs.

Example workflows

Run the Codex CLI in a repo and ask it to implement a function with tests
Send a cloud task from the web and review the resulting PR

What can it do?

Codex CLI and IDE extensionLocal agent; also works with an API key.
Cloud tasks Depends on planRequires ChatGPT sign-in; not available with API-key usage.
Desktop app LimitedFree and Go users get GPT-6 Luna in the desktop app, rollout-dependent.
Fast and Ultrafast modes Depends on planUse allowance faster; Ultrafast on the $500 Pro tier.
Extra credits Depends on planPlus users and Business workspaces can buy additional credits.

Good for

Feature implementation
Code review
Bug fixing
Parallel cloud tasks

Where it runs

Desktop appCLIIDE extensionWebiOS

Pricing and plans

Free plan + paid Codex is included in ChatGPT Free, Go ($8), Plus ($20), Pro (from $100), Business ($25 per user monthly or $20 annually) and Enterprise/Edu plans. Usage limits rise with the plan. API-key usage is billed separately at standard API token rates.

Plan	Price	Billing	Free trial / tier	Usage limits	Main inclusions	Model access	API access	Restrictions
Free	Free	per month	Free tier	Quick coding tasks	GPT-6 Luna in desktop app (rollout-dependent)	GPT-6 Luna	—	Light use only
Go	$8/mo	per month	—	Lightweight coding	GPT-6 Luna in desktop app (rollout-dependent)	GPT-6 Luna	—	—
Plus	$20/mo	per month	—	Estimated local messages per 5 hours: GPT-6.1 Sol 15-160, GPT-6 Astra 5-45, GPT-6 Luna 350-3,000; weekly limits may apply	Web, CLI, IDE and iOS Buy extra credits	GPT-6.1 Sol, GPT-6 Astra, GPT-6 Sol, GPT-6 Luna	Separate	—
Pro	$100/mo Tiers at $100, $200 and $500 per month	per month	—	No five-hour limit currently	Ultrafast mode on the $500 tier	Full Codex model list	Separate	—
Business	$25/mo $20/mo billed annually Per user; 2+ users	per month	—	Similar estimates to Plus for Standard Business	Shared workspace Credit top-ups	Full Codex model list	Separate	Minimum 2 users
Enterprise / Edu	Contact provider	usage-based	—	Flexible credit-based pricing with no fixed rate limits	Admin controls	GPT-6.1 Sol off by default until an admin enables it	—	—

Prices in USD · US / global list price · Taxes may apply · Verified Oct 19, 2026

Worked example (usage-based API pricing): sending 1,000,000 input tokens and receiving 200,000 output tokens at the listed gpt-6.1-sol rates ($2 and $10 per 1M) costs about $4 before tax. Real bills depend on the model, caching, batch discounts and any tier you qualify for.

Official pricing page (opens in a new tab)

API and developer access

Official API: Yes
Documentation: API docs (opens in a new tab)
Authentication: API key
Pricing model: per 1M tokens
Free API quota: None documented — the free plan above (if any) is for the app, not the API
Rate limits: Not documented
Context / input limits: Not documented
SDKs: Codex SDK
Streaming: Not documented
Batch processing: Not documented
Structured output: Not documented
Tool / function calling: Not documented
Commercial use: See the provider terms
Data retention & privacy: See the provider privacy terms

Published API rates

Item	Price	Unit
gpt-6.1-sol input	$2	per 1M input tokens
gpt-6.1-sol cached input	$0.10	per 1M input tokens
gpt-6.1-sol output	$10	per 1M output tokens
gpt-6-luna input	$0.10	per 1M input tokens
gpt-6-luna output	$0.50	per 1M output tokens
gpt-6-astra input	$10	per 1M input tokens
gpt-6-astra output	$50	per 1M output tokens
gpt-5.3-codex input	$1.75	per 1M input tokens
gpt-5.3-codex output	$14	per 1M output tokens

A free OpenAI Codex account is not the same thing as free API access. Unless a free API quota is listed above, API calls are billed separately.

Verified Oct 19, 2026

Advantages and disadvantages

Advantages

Bundled with ChatGPT subscriptions
Wide range of models and speed modes
Works with API key for local use

Disadvantages

Usage per 5-hour window is an estimate and varies by model and task
Cloud features not available with API key
Free and Go tiers are for light use

Privacy: Enterprise and Edu admins control model availability. API-key usage follows OpenAI API data terms.

Real-world examples

A hobbyist fixing a small script

Sign in to the Codex desktop app with a free ChatGPT account
Describe the bug
Apply and test the suggested change

free plan works

A developer using Codex in the terminal with an API key

Install the Codex CLI
Set an OpenAI API key
Ask it to add tests to a module; billed at API token rates

needs API key

A startup team sharing Codex

Create a ChatGPT Business workspace
Connect repositories
Assign cloud tasks and review PRs

needs paid plan

OpenAI Codex alternatives

Claude Code

Anthropic's agentic coding tool that reads your codebase, edits files and runs commands from the terminal, IDE, desktop or browser.

no free plan · offers an API

OpenAI Codex vs Claude Code

GitHub Copilot

An AI pair programmer and coding agent that works in your editor, terminal and on GitHub itself.

has a free plan · no public API

OpenAI Codex vs GitHub Copilot

Cursor

An AI-first code editor with local and cloud agents, now sold on a shared Cursor and Grok subscription.

has a free plan · offers an API

OpenAI Codex vs Cursor

Devin Desktop (formerly Windsurf)

The renamed Windsurf editor, rebuilt around managing local and cloud coding agents.

has a free plan · offers an API

OpenAI Codex vs Devin Desktop (formerly Windsurf)

Compare OpenAI Codex with these side by side

Frequently asked questions

Is Codex free?

ChatGPT Free includes Codex for quick tasks, with GPT-6 Luna in the desktop app depending on rollout. Heavier use needs a paid plan.

Which ChatGPT plans include Codex?

Free, Go, Plus, Pro, Business, Edu and Enterprise all include Codex, with higher limits on higher plans.

What is the latest model in Codex?

GPT-6.1 Sol is listed as the flagship Codex model; GPT-6 Astra, GPT-6 Sol and GPT-6 Luna are also offered.

Can I use Codex with an API key?

Yes, in the CLI, SDK and IDE extension, billed at standard API token rates. Cloud features are not included with API-key use.

Are the usage limits fixed?

No. OpenAI gives estimated message ranges per five-hour window that vary by model and task; weekly limits may also apply. Pro currently has no five-hour limit.

Is GPT-5.5 still available in Codex?

OpenAI states GPT-5.5 retires from Codex with ChatGPT sign-in on October 14, 2026; API-key sessions are not affected.