You can find the API key in the Contlo Dashboard.
Authentication to the API is performed by passing X-API-KEY in the header section.
X-API-KEY: <api_key>
All API requests must be made over HTTPS. Calls made over plain HTTP will fail. API requests without authentication will also fail. Your api keys carry many privileges, so be sure to keep them a secret.
Use a private key for all backend api specific requests. Use the public key if you are sending events from the website or frontend via javascript.