In order to ensure the security of your data, the Mixpanel API requires a basic system of authentication in order to consume your data. This involves your project token, key, and secret.
Your project token is used whenever you want to send data (events or people) to Mixpanel. You can find your project token by clicking your name in the upper righthand corner of your Mixpanel project and selecting Project settings or Account > Projects from the dropdown.
Your token is public, and is the only project-specific object required to send data to Mixpanel.
Since Mixpanel users can have multiple projects, and each project has it's own project token, whenever you want to send data to a specific project, you'll need to specify the project token so we know where to send the data.
Your API key acts as both a unique identifier and a token for authentication. It will generally have a set of access rights on the API associated with it.
Your API key will correspond to the project you wish to consume from.
This is a secret API key corresponding to your project. You should never share this API secret or send it over email. You can find your API secret by clicking your name in the upper righthand corner of your Mixpanel project and selecting Project settings or Account > Projects from the dropdown.
You will use your secret to sign an API call, and it is required this to extract data from your Mixpanel project.