Customer.io is a REST API. This connector has the following streams:
- Campaigns (Incremental)
- Campaign Actions (Incremental)
- Newsletters (Incremental)
See here for API documentation. Note that the API is divided into three different API hosts: Track, App, and Beta. These hosts provide access to different components of Customer.io, and each host has its own request limits and authentication methods. The current connector streams all use the Beta API. In the future, additional streams may use the other API hosts.