Use your ChatGPT account or a Claude or Grok API key with Tera Chat for free

Tera Chat’s AI features are free to use with your own AI: connect your ChatGPT account through OpenAI’s Codex, or paste a Claude (Anthropic) or Grok (xAI) API key, in Settings → API Keys. Tera Chat charges nothing for this; you pay your provider, and a daily spend cap ($5 by default) limits what an API key can spend. One catch: Tinder and Instagram reply drafts only work with ChatGPT through Codex or a Tera Chat AI plan.

Below: which option to pick, the setup steps for each, what it costs you, where your messages go, and what to do when something doesn’t work. If you’d rather not set anything up, the built-in Tera Chat AI plans do the same job for a monthly price.

Which AI option should you pick?

If you already pay for ChatGPT, start with Codex: it’s included in your plan and it’s the only own-account option that drafts Tinder and Instagram replies. Pick a Claude or Grok key if you prefer those models or want pay-per-use billing. Prices and plan details below are as of October 2026.

Option	What you need	What it costs you	Tinder and Instagram drafts	Best for
ChatGPT through Codex	A ChatGPT account and OpenAI’s Codex installed on your Mac	Included in ChatGPT plans (Free, Go, Plus, Pro, Business, Edu, Enterprise), within each plan’s usage limits (OpenAI)	Yes	People who already use ChatGPT
Claude API key	A Claude Console account with billing set up	Pay per use, billed by Anthropic separately from Claude Pro (Anthropic)	No	Claude fans; Claude Max subscribers with API credits
Grok API key	An xAI console account with credits loaded	Pay per use from the credits you load (xAI)	No	Grok users
Tera Chat AI plan	Nothing to set up	From $9.99 a month, cancel anytime	Yes	People who don’t want to manage accounts

What you get with your own AI

Bringing your own AI turns on the same AI features as a plan (Autopilot and Tinder and Instagram drafts need the Codex option):

• Replies in your style: drafts that match your slang, emoji and message length. Click the sparkle button in an empty reply box to get one. You edit and send.
• A different tone for different people: tag contacts (family, colleague, crush, VIP and so on) and give each tag its own tone in Settings → AI Replies → Tag overrides.
• Summarize (⇧⌘S) any thread you’ve fallen behind on.
• Ask about this chat: questions like “did they ever mention their birthday?”, answered from the last 50 messages and what Tera Chat knows about the person.
• Voice drafts (⌥⌘V): pick the audio file of a voice message someone sent you; Tera Chat transcribes it on your Mac and drafts your reply to it.
• Life events and the weekly digest, which need AI to run.

Plenty works without any AI set up at all: the inbox and search, missed cues, fading-chat alerts, circles and goals, introductions, red-flag radar and the health score (its tone part uses AI only if you’ve set it up).

How to connect ChatGPT through Codex

Codex is OpenAI’s coding agent, and it’s how Tera Chat uses your ChatGPT account without ever seeing an OpenAI password or key. There’s no ChatGPT sign-in inside Tera Chat: Tera Chat runs Codex on your Mac, and Codex uses the ChatGPT login it has saved.

1. Install Codex. Either install OpenAI’s ChatGPT desktop app for Mac, which includes Codex (OpenAI), or install the Codex command-line tool using the command on OpenAI’s Codex CLI page. Tera Chat looks for Codex in the usual places: the ChatGPT or Codex app in your Applications folder, the command-line tool’s install folders and Homebrew.

2. Sign in to Codex with your ChatGPT account. With the command-line tool, run this in Terminal:

   codex login
   

   A browser page opens; sign in with ChatGPT. codex login status shows whether you’re signed in (OpenAI). In Tera Chat, the Manage Codex login in Terminal link opens Terminal for this. If you only use the desktop app, sign in there; if Tera Chat’s drafts then fail, install the command-line tool and run codex login as well.

3. Turn it on in Tera Chat. Open Settings (⌘,) → API Keys and switch on Codex / ChatGPT. The note under it reads “Uses your local Codex CLI ChatGPT login. No OpenAI API key is stored in Tera Chat.”

4. Optionally pick a model and effort. Effort runs from Low to Max; High is the default.

5. Check the status line. It shows Active: followed by the provider and model Tera Chat is using.

How to add a Claude (Anthropic) API key

1. Sign in to the Claude Console and set up billing.
2. Open the API keys page in the Console and create a key. Copy it: it starts with sk-ant-.
3. In Tera Chat, open Settings → API Keys. Under API-key fallbacks, paste the key into Anthropic and choose a model.

A Claude Pro subscription doesn’t cover API use: Anthropic bills the API separately. If you pay for Claude Max (5x or 20x) or a Team plan, though, Anthropic adds monthly API credits ($100 a month on Max 5x, $200 on Max 20x) once you link a Console organization to your plan, and a key from that organization draws on them (Anthropic). Unused credits don’t roll over. For what Claude can and can’t do with your chats on its own, see can Claude reply to your WhatsApp messages?

How to add a Grok (xAI) API key

1. Create an account at the xAI console (console.x.ai) and load it with credits (xAI).
2. Open the API Keys page and create a key. It starts with xai-.
3. In Tera Chat, open Settings → API Keys and paste it into xAI Grok.

What does it cost, and how does the daily spend cap work?

With Codex, Tera Chat’s AI use counts against your ChatGPT plan’s limits, the same way your own Codex use does. OpenAI says the number of messages you can send “depends on the model used, size and complexity of your tasks”, and Plus and Pro users can buy more credits when they run out (OpenAI).

With a Claude or Grok key, you pay per use at your provider’s rates (Anthropic pricing). To stop a surprise bill, Tera Chat has a Daily spend cap in Settings → General: anywhere from $1 to $50 a day, $5 by default. It applies to your own API keys, and background AI jobs respect it too. The menu bar popover shows what you’ve spent today.

Which AI does Tera Chat use if you have several?

Tera Chat picks in this order: a Tera Chat AI plan, then Codex / ChatGPT, then your Anthropic key, then your Grok key. If you have a plan but want to use your own AI instead, turn off Use Tera Chat AI for AI features in Settings → Tera Chat AI.

One exception: the Draft reply sheet (⌥⌘D) compares drafts side by side, and in iMessage, WhatsApp and Telegram chats it only uses Codex / ChatGPT and a Grok key. With only a Claude key (or only a Tera Chat AI plan), it asks you to enable Codex or add a Grok key; use the sparkle button in the empty reply box instead, which works with every option.

Where do your messages go?

AI sees the conversations it works on. With your own account, that text goes straight from your Mac to the provider you picked, under that provider’s own terms. Anthropic, for example, says it won’t use inputs or outputs from its commercial products, which include the API, to train its models by default (Anthropic). For ChatGPT, your account’s own data settings apply.

A few more things to know:

• Some AI runs in the background once it’s set up: a summary after every 10 new messages, a daily check for life events, and the Sunday digest. Pause it in Settings → Pipelines → Pause processing.
• Your Claude and Grok keys are stored in the macOS Keychain. Tera Chat stores no OpenAI key.
• Voice transcription and red-flag radar run on your Mac, with no AI provider involved.
• Your messages themselves stay on your Mac and are never uploaded to a Tera Chat server.

If you want to weigh this properly, Is it safe to let AI read your messages? compares the privacy models, and Is Tera Chat safe? covers the app as a whole.

How do you make the drafts sound like you?

Tera Chat learns your style from messages you’ve sent. To refresh it, open Settings → Writing Style and click Retrain now: it reads up to 2,000 of your sent messages, works out your phrases, emoji habits and languages on your Mac, uses AI to write a short description of your style, and picks 30 example messages to imitate. For more on why AI replies sound robotic and how to fix it, see AI that replies to texts in your style.

If something goes wrong

Problem	Fix
The Codex / ChatGPT switch doesn’t work	Make sure Codex is installed (the ChatGPT app or the command-line tool) and signed in. If you’re not sure, install the command-line tool, run codex login in Terminal and try again
⌥⌘D says to enable Codex / ChatGPT or add a Grok key	The Draft reply sheet doesn’t use Claude keys or Tera Chat AI in iMessage, WhatsApp and Telegram chats
A Tinder or Instagram chat says “Conversation drafting requires Tera Chat AI or the Codex / ChatGPT connection”	Claude and Grok keys aren’t used there. Turn on Codex / ChatGPT, or start a Tera Chat AI plan
AI stopped working partway through the day	You may have hit the Daily spend cap. Raise it in Settings → General, or wait until tomorrow
Codex drafts stop working after heavy use	You may have used your ChatGPT plan’s Codex allowance for now. Wait for it to reset, or add a Claude or Grok key as a fallback
A Claude or Grok key is rejected	Check you copied the whole key and that your account has billing or credits set up
The status line shows a provider you didn’t expect	Tera Chat uses the first available option in order: Tera Chat AI, Codex, Anthropic, Grok

What to do next

Once AI is on, open a chat you owe a reply to and click the sparkle button in the empty reply box. If you haven’t connected all your apps yet, the getting started guide walks through it, and if you’re comparing costs, Tera Chat AI plans explained sets the plans against your own account.