Every Klaviyo account has one Public API Key, and can have multiple Private API Keys.
To access your account's API keys, navigate to Account > Settings > API Keys.
Public API Key
Your Public API Key, or Site ID is a short alphanumeric value. This key does not access any data within your account, so it is safe to expose to the public
Private API Key
Private API keys should be kept safe from the public because they give access to data and sensitive objects such as lists within your Klaviyo account.
You can generate new Private API Keys for different application uses. This can help trace the source of data being added to your Klaviyo account via the API.