Write your Threadgehog posts with your ChatGPT plan

Already pay for ChatGPT Plus or Pro? Threadgehog can write with that plan instead of an API key. It runs Codex on your Mac, signed in to your own ChatGPT account, and each draft counts toward your plan's usage limits. Setup takes about 2 minutes: install Codex, sign in once, then press Test. Available from Threadgehog 1.1. Last updated October 5, 2026.

How to set up ChatGPT subscription (Plus or Pro)

  1. Choose ChatGPT in Settings > AI

    In Threadgehog, open Settings (⌘,) and click the AI tab. The same cards appear in step 2 of first-time setup. Click "Use my Claude or ChatGPT subscription", then "ChatGPT subscription (Plus or Pro)". Threadgehog checks whether Codex is on this Mac and shows the next step.

    Connect an AI with Use my Claude or ChatGPT subscription selected and ChatGPT subscription (Plus or Pro) chosen: Codex is installed and signed in, with the Test button

  2. Install Codex

    If Threadgehog says "Codex isn't installed on this Mac.", click Copy next to the install command, paste it into Terminal and press Return. Without Homebrew, use npm install -g @openai/codex instead. When it finishes, go back to Threadgehog and press Check again.

    brew install --cask codex
    ChatGPT plan chosen while Codex isn't installed on this Mac, showing brew install --cask codex and the npm alternative, with Copy and Check again buttons

  3. Sign in to your ChatGPT account

    If Threadgehog shows "Sign in once in Terminal:", paste this command into Terminal. It opens OpenAI's own sign-in page in your browser. Sign in with the account that has your Plus or Pro plan, then press Check again in Threadgehog.

    codex login
    ChatGPT plan chosen with Sign in once in Terminal and the codex login command, with Copy and Check again buttons

  4. Press Test

    When Threadgehog shows "Codex is installed and signed in.", press Test. It asks Codex for one short reply and shows how long it took, for example "Works (2.1 s)". From then on, Threadgehog writes with your plan.

    ChatGPT plan after pressing Test: Codex is installed and signed in, and the result reads Works (2.1 s)

What you get

  • Your plan writes everything: the daily drafts, the first batch at setup, and Write drafts.
  • No API key, and no extra charge from Threadgehog. Drafts count toward your ChatGPT plan's usage limits.
  • Threadgehog uses Codex's default model.
  • Switch to your own API key or Threadgehog AI any time in Settings > AI.

What it costs

Threadgehog charges nothing extra to write with your plan. You keep paying for ChatGPT Plus or Pro as usual, and each draft uses part of that plan's usage limits, so a day of 100 or more drafts can reach a limit sooner. Your Threadgehog plan still includes its monthly Threadgehog AI drafts, and you can switch to them in Settings > AI if your ChatGPT limit runs out.

Your key and your data

Threadgehog never sees or stores your ChatGPT login. You sign in through Codex in Terminal, on OpenAI's own sign-in page, and Codex keeps that sign-in on your Mac. Each writing step still goes through Threadgehog's server at api.threadgehog.com, which prepares the request from your brand voice, brief and rules and stores nothing you write. To stop, pick another option in Settings > AI. Your saved API keys stay in Keychain.

Limits to know

  • Needs a paid ChatGPT plan: Plus or Pro.
  • Needs Codex installed on this Mac. Threadgehog connects to your plan through Codex, signed in once in Terminal.
  • Threadgehog writes while it is open, the same as with any other option; turn on Open Threadgehog when you log in to keep it running after a restart.
  • When your plan's usage limit is reached, Threadgehog says so and tries again later. You can switch to Threadgehog AI in Settings > AI instead of waiting.

Troubleshooting

"Codex isn't installed on this Mac."

Why: Threadgehog couldn't find Codex.

Fix: Copy the install command from Settings > AI into Terminal and run it, then press Check again.

"Codex isn't signed in. Open Terminal, run codex login, then try again."

Why: Codex is installed but signed out, or its sign-in expired.

Fix: Run codex login in Terminal, sign in with your Plus or Pro account, then press Check again.

"Your plan's usage limit is reached. Threadgehog tries again later, or switch to Threadgehog AI in Settings > AI."

Why: Your ChatGPT plan hit its usage limit.

Fix: Wait for the limit to reset and Threadgehog picks up again, or switch to Threadgehog AI in Settings > AI.

"Codex took too long to respond. Try again."

Why: Codex didn't answer in time.

Fix: Try again. If it keeps happening, press Test in Settings > AI to check the connection.

"The connection test failed. Check your sign-in in Terminal, then try again."

Why: Codex couldn't complete the test request.

Fix: Run codex login in Terminal to refresh your sign-in, then press Test again.

Questions

Do I need an API key?

No. Your ChatGPT plan takes its place. Threadgehog runs Codex on your Mac, signed in to your plan.

Which ChatGPT plans work?

Plus or Pro, the plans Codex signs in with. Without one, use Threadgehog AI, which every Threadgehog plan includes, or your own API key.

What happens when I reach my plan's limit?

Threadgehog says your plan's usage limit is reached and tries again later. To keep writing right away, switch to Threadgehog AI in Settings > AI.

Is this the same as connecting Codex in Settings > Agents?

They do different jobs. Here, Threadgehog uses Codex to write its own drafts. In Settings > Agents, you use Codex to run Threadgehog from your terminal: list projects, write and approve posts, send the queue. You can use both at once.

Can I switch back?

Yes, any time in Settings > AI. Pick Use my own AI key or Threadgehog AI. Keys you saved before stay in your Mac's Keychain.

Other guides