Decile Hub provides an API to connect with different services, like the Browser Plugin and Zapier. You may be asked for an API key to enable these offerings, which you can get below:

Follow the instructions on Decile Hub to set up the API key, and then copy the API key from Decile Hub and paste it into the field requesting it.

Decile Hub users are given access to the API when they sign-up for 2 months as part of a free trial. The API, as well as other premium features, are then part of premium packages, which you can learn more about here.