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OpenAI API key

Create an OpenAI API key and connect it to Cella.

What you need

You need a Cella Max plan, an internet connection, and an OpenAI API Platform account. An OpenAI API key is not included with a ChatGPT subscription. API usage has separate billing and limits.

Good to know: An API key is a secret that can spend money on your provider account. Create a dedicated key for Cella, do not share it, and delete it immediately if you think it has been exposed.

Create the key in the OpenAI Platform

  1. Open OpenAI API keys and sign in.
  2. Select the API project you want Cella usage to belong to. A dedicated project can make costs and limits easier to track.
  3. Select Create new secret key.
  4. Give the key a clear name, such as Cella iPhone.
  5. If the form asks for permissions, make sure the key can list models and make model requests. The default permissions are the simplest choice for a personal setup.
  6. Create the key, then copy the full secret immediately. OpenAI does not show the full value again after you close the dialog.

If the account has no API balance or payment method, open the API Platform billing settings and add billing before testing in Cella. A ChatGPT payment method does not automatically apply to API usage.

Add the key to Cella

  1. In Cella, open More > Settings > AI Engine.
  2. Under Cloud Providers, tap Add Cloud Provider.
  3. Set Provider to OpenAI.
  4. Leave Display name as OpenAI, or enter a name that identifies this API project.
  5. Paste the secret into API key. Do not add spaces before or after it.
  6. Tap Choose model and select a current general-purpose model returned for your key.
  7. Tap Test connection.
  8. When Cella shows Authenticated, structured output and chat tools verified, tap Save.

Cella stores the key in the iOS Keychain. When you select this provider for a vault, relevant document content is sent directly from your iPhone to OpenAI under your OpenAI account and terms.

If the connection fails

  • API key was rejected: Copy the key again, remove accidental spaces, and confirm it has not been deleted.
  • No models appear: Check that the key belongs to the intended project and has permission to list and use models.
  • Rate limited or quota error: Check the API project's billing balance, spend limit, and rate limits. ChatGPT subscription status does not change API limits.
  • Structured output or tools are unsupported: Return to Choose model and select another current general-purpose model.

For current provider instructions, see the official OpenAI quickstart and OpenAI API keys.