Is Codex Free? OpenAI Codex Free Access, Credits & Pricing (2026)

Codex is partly free. On ChatGPT Free and Go, OpenAI lets you run quick, lightweight coding tasks with GPT-6 Luna at Standard speed in the Codex desktop app, though this is still rolling out. The full Codex product (web, CLI, IDE extension, iOS and cloud integrations such as automatic code review and Slack) starts with ChatGPT Plus at $20/month.

The Codex CLI is open source (Apache-2.0) and free to install, but running it still needs either a ChatGPT sign-in (which uses your plan's limits) or an OpenAI API key billed at standard API rates. Verified university students in the US and Canada can also claim $100 in Codex credits, which is the biggest genuinely free route right now.

Codex access by ChatGPT plan

Codex isn't sold as a separate subscription. It's part of your ChatGPT account, so the plan you already have decides what you can do. This is how OpenAI's official Codex pricing page lists each plan:

OpenAI doesn't publish usage numbers for Free or Go, and both are described as "subject to rollout", so not every free account may see Codex yet. Prices are in US dollars; Go and Plus are priced differently in some countries. For the full plan comparison, see Codex pricing and ChatGPT pricing.

What Free and Go users don't get

• No Codex cloud. Cloud tasks, automatic GitHub code review and the Slack integration start with Plus.
• No CLI, IDE extension or web access through the plan. OpenAI lists these surfaces from Plus upward. Free users can still use the CLI or IDE extension by signing in with an API key, but that is paid API usage, not free Codex.
• Only GPT-6 Luna. The stronger GPT-6.1 Sol and GPT-6 Astra models aren't listed for Free or Go.
• No image generation in Codex on Free. OpenAI's pricing page says image generation isn't available on the Free plan.
• No option to buy credits. OpenAI says Plus and Pro users can buy extra credits when they hit their limits; Free and Go aren't included.

Codex usage limits on Plus

OpenAI gives estimated ranges of local messages per five hours for Plus and standard Business seats. These are estimates, not fixed caps, and OpenAI says weekly limits may also apply without publishing weekly figures:

The ranges are wide because a "message" can be a one-line edit or a long agentic task that reads dozens of files. OpenAI says the model, context size, reasoning, tool use, retrieval and caching all change how much a task consumes, and that cloud tasks may use more of the allowance than local messages. Code review only counts against the review allowance when it runs through GitHub; local reviews count toward your general limits.

Speed modes eat into limits faster

Ultrafast is only available on Pro $500 and eligible Enterprise and Edu plans. Pro currently has no 5-hour limit at all. Usage is also shared with other agentic features once their pricing takes effect; OpenAI names ChatGPT for Excel on Plus and Pro as one of them.

Stretching a plan's limits

OpenAI's own tips for making limits last: keep prompts short, limit how much source material you hand Codex, say exactly what output you need, keep your AGENTS.md file small, and switch off MCP servers you aren't using. In practice, routing routine edits to GPT-6 Luna and saving GPT-6.1 Sol or GPT-6 Astra for harder problems makes the biggest difference, because Luna's allowance is roughly 20 times larger.

How Codex credits work

When Plus or Pro users hit their limits, they can buy credits to keep going without upgrading. Business, Edu and Enterprise workspaces with flexible pricing can buy workspace credits. Student credits use the same system. Credits are used up per million tokens at Standard speed:

Figures are credits per 1M tokens. There's no separate charge for writing to the cache. OpenAI doesn't publish a fixed dollar price per credit for purchases; it says purchase prices and discounts depend on your plan or agreement. Voice in the desktop app costs $0.05 per minute from your Codex budget, or 1.25 credits per minute when you're spending credits, and the model handling the task is billed on top at its token rates.

Worked example: what 2,500 credits buys

Take a hypothetical coding session that sends 2 million input tokens (1.5 million of them served from cache) and gets 100,000 output tokens back. Using OpenAI's credit rates:

With the 2,500 credits from the student offer, that's about 869 such sessions on GPT-6 Luna (2,500 / 2.875), about 46 on GPT-6.1 Sol (2,500 / 53.75), or about 8 on GPT-6 Astra (2,500 / 287.5). Real sessions vary a lot, so treat this as a way to compare models, not a promise. Your live balance is shown on the Codex usage page in settings.

For comparison, OpenAI's API list price for GPT-6.1 Sol is $2 input, $0.10 cached input and $10 output per 1M tokens, so the same session would cost $2.15 with an API key. The credit rates work out to 25 credits per API dollar for each of these models, which matches the student offer's "$100 = 2,500 credits". OpenAI doesn't say that ratio applies when you buy credits.

How to get Codex for free

1. ChatGPT Free: sign in to the Codex desktop app with a free ChatGPT account for quick GPT-6 Luna tasks, where the rollout has reached you.
2. Students in the US and Canada: OpenAI offers current students at degree-granting universities $100 in Codex credits (shown as 2,500 credits), verified through SheerID. Credits expire 12 months after they're granted. See Codex credits for students.
3. ChatGPT Plus student offer: eligible US college and graduate students can get four free months of Plus, which includes full Codex, if they claim by October 31, 2026. A payment method is required and Plus renews at $20/month afterwards unless cancelled. See the ChatGPT Plus student offer.
4. Open-source maintainers: OpenAI's Codex for Open Source program offers six months of ChatGPT Pro with Codex to core maintainers of widely used public projects, API credits from the $1 million Codex Open Source Fund for projects using Codex in review or release workflows, and case-by-case Codex Security access. No deadline is listed and the page invites applications.
5. Startups: startups backed by VCs in OpenAI's partner network may get free API credits, which can pay for Codex used with an API key. See OpenAI for Startups.
6. Referrals: OpenAI's Codex pricing page says eligible users can send invites from the profile menu ("Invite a friend" on personal plans, "Invite a coworker" in eligible Business workspaces). The dialog shows the current reward and rules; OpenAI doesn't list reward amounts publicly, and Enterprise isn't eligible.

Claiming the student credits, step by step

1. Sign in to ChatGPT with a personal Free, Go, Plus or Pro account. It doesn't need to be linked to your school.
2. Open the offer from OpenAI's Codex for Students page and select Claim now.
3. Verify with your university email through SheerID. You must be a current student and live in the US or Canada when claiming.
4. Once verification succeeds, the credits are added to your ChatGPT account automatically. Check them on the Codex usage page in settings.
5. Use them within 12 months. They are ChatGPT credits for Codex, not OpenAI API credits, so they don't work with an API key.

Both student offers are separate. The $100 Codex credits are open to US and Canadian university students and don't require Plus. The four free Plus months are US-only and end on October 31, 2026. Eligible US students can use both.

Using Codex with an API key

You can skip the subscription and sign in to the Codex CLI, SDK, IDE extension or desktop app with an OpenAI API key. Usage is then billed at standard OpenAI API pricing and follows your API organization's data settings. OpenAI's API pricing page doesn't list free signup credits, so this route isn't free unless you already have credits (for example from a startup program).

These are OpenAI's standard list prices for requests up to 272K input tokens. The hypothetical session above would cost about $0.12 on GPT-6 Luna and $2.15 on GPT-6.1 Sol. Light users may spend less than $20 a month this way; anyone coding daily will usually get more out of Plus.

What you lose with an API key: Codex cloud (which requires ChatGPT sign-in), GitHub code review and Slack, desktop voice, and some OpenAI-curated plugins whose sign-in flows don't support API keys.

Installing and signing in

# install (pick one)
npm i -g @openai/codex
brew install --cask codex
curl -fsSL https://chatgpt.com/codex/install.sh | sh

# sign in with your ChatGPT plan
codex            # choose "Sign in with ChatGPT"

# or sign in with an API key
printenv OPENAI_API_KEY | codex login --with-api-key

# check or clear the active login
codex login status
codex logout

Windows users can install with OpenAI's PowerShell script from the repository README. On a headless server, OpenAI recommends device code login (codex login --device-auth, which you first enable in ChatGPT security settings). Credentials are stored in ~/.codex/auth.json or the OS credential store. That file contains access tokens, so never commit or share it.

Recent changes worth knowing

• February 2026: OpenAI launched the Codex desktop app and gave Free and Go users temporary access as a limited-time promotion, while doubling rate limits on paid plans (per OpenAI's Codex app announcement).
• April 9, 2026: OpenAI added a $100/month Pro tier with 5x Plus usage, alongside the $200 tier at 20x. A launch bonus of up to 10x Plus usage on the $100 tier ran until May 31 and has ended (reporting: 9to5Mac). OpenAI's pricing page now also lists a $500 Pro tier with Ultrafast mode.
• 2026: Codex moved to token-based credit rates (credits per 1M tokens), replacing flat per-message pricing. A small set of Enterprise customers remain on a legacy rate card until migrated.
• October 14, 2026: GPT-5.5 was retired from Codex for ChatGPT sign-in. API-key sessions weren't affected.
• Ongoing: OpenAI says GPT-5.6 Sol promotional credit pricing runs at least through November 21, 2026.

Codex vs other coding agents

If you're choosing a coding agent mainly on price, here's how the free routes compare at a glance. Check each linked page for current limits:

For more ways to cover AI coding costs, including API free tiers you can plug into open-source agents, see our guides to free AI API keys and getting free AI credits.

Troubleshooting free access

• Codex doesn't appear on my Free account. OpenAI says Free and Go access is subject to rollout. Update the desktop app and check again later; there's no published date for full availability.
• The CLI asks me to upgrade. Signing in with ChatGPT on Free or Go doesn't unlock the CLI. Either upgrade to Plus or log in with an API key (which is billed).
• I hit my limit quickly. Switch to GPT-6 Luna, turn off Fast mode (it uses included usage 2.5x faster), and trim large context such as long AGENTS.md files and unused MCP servers.
• Student credits don't show up. Credits only appear after SheerID verification succeeds, and they're tied to the ChatGPT account you used to claim. Check the usage page in Codex settings.
• Cloud tasks fail with an API key. Codex cloud requires ChatGPT sign-in; API keys only cover local work.

If you code lightly, start with ChatGPT Free in the desktop app. If you code most days, Plus at $20/month is the cheapest full Codex plan. Students should claim the $100 credit offer first, and US students should also check the free Plus months before October 31, 2026.