Use your ChatGPT session as a Codex account
Your ChatGPT plan has two separate allowances behind it. Codex tasks spend one; chatting spends the other. A ChatGPT Web account in CodexUse answers Codex tasks from the second one.
What it is
A ChatGPT Web account is a normal CodexUse account with a different thing answering the model. Instead of a Codex model or a third-party provider, the answer comes from your own ChatGPT session, through the ChatGPT session already open in your regular Google Chrome profile. CodexUse creates and drives separate background tabs for its tasks. It gets its own Codex window and its own Codex home, exactly like every other account.
Because the turn happens in a chat, it spends the Chat allowance. No OpenAI account’s Codex allowance is touched, and no provider bills you.
What you need
- An Apple Silicon Mac on macOS 13 or newer.
- A ChatGPT subscription that carries the models you want. CodexUse publishes only the routes it observes in your own session, so what you get is what your plan shows you.
- One OpenAI account already signed in to CodexUse on the same Mac. CodexUse publishes Web models to Codex using the shape of a native Codex model, and it needs a real Codex catalog to copy that shape from.
- An OpenAI Tunnel and a regular secret OpenAI API key with Tunnels Read + Use in the same API organization. The key is the
sk-…value shown once when you create it, not an Admin key or a URL. - ChatGPT Developer Mode, so you can create the connector.
- Google Chrome 116 or newer with the bundled CodexUse Chrome Companion enabled.
That list is the honest cost of this feature. It is more setup than adding an OpenAI account, and most of it happens on platform.openai.com and inside ChatGPT rather than in CodexUse.
Set it up
- Prepare the OpenAI connection. Create an OpenAI Tunnel. Then create a regular secret key under API keys in the same organization and grant only Tunnels Read and Use.
- Use the connection form. In CodexUse choose Accounts, Add account, ChatGPT Web. Choose Open Chrome setup once. CodexUse refreshes its bundled companion in one stable local folder, opens Chrome Extensions, reveals that folder, and copies its path. Turn on Developer mode, choose Load unpacked, press Command-Shift-G in the folder chooser, paste the copied path, and select the folder. Then name the account, paste the tunnel ID and secret API key, and start setup. CodexUse validates both values, connects to the signed-in regular Chrome profile, detects models, and starts the runtime automatically.
- Use the Connector screen. Open ChatGPT settings, turn on Developer Mode, create a Tunnel connector for that tunnel, name it exactly CodexUse, set Authentication to None and Permissions to Allow all actions, then return and check it. CodexUse sends one real tool-backed turn before it marks the account ready.
What it looks like when it works
The account appears in Accounts under its own group, with Chat allowance where an OpenAI account shows a headroom percentage. Its detail page lists the Web models it verified, the connection rows, the result of the last connection check, and the recent browser turns with the time each step took. A slow or stuck turn is visible there without reading a log.
From then on it behaves like an account. Open gives it a Codex window. It can be the worker in a Work run. Interrupting a Codex turn also abandons the browser turn.
What it cannot do
- Show you how much is left. ChatGPT reports no authoritative remaining percentage for this route, so CodexUse shows none and never adds it to Codex usage.
- Join percentage-based auto-roll or Account Pool. Both rank accounts by headroom, and this account has no headroom number to rank.
- Replace an OpenAI account. Setup needs one, and removing it does not leave the Web account able to publish models.
- Run on Intel Mac, Windows, or Linux. ChatGPT Web support is macOS on Apple Silicon only and requires Chrome 116 or newer with the bundled companion enabled.
- Give you a model your plan does not have. The catalog contains only routes observed in your own session.
If it breaks
Almost every failure at the connector step is the connector name. It has to be exactly CodexUse, and only one connector may carry that name. After that, the usual causes are an API key without Tunnels Use, or a key and tunnel in different API organizations. Repair runtime restarts the sidecar, helper, and tunnel client, reconnects to Chrome, and repeats verification; Recheck login and models is the lighter check when the sign-in may have lapsed.