Content API
Content API feature enables you to configure your API end points in Connect and use it to fetch any data and use it in your campaigns.
To add a content API, go to Profile (top right corner) -> Settings -> Content API.
How to add and test a Content API
In the popup, enter a API name and add API cuRL request with placeholders (if any) and click Validate. 

If there any placeholders present in the API Request, then its recommended to add a description for the same.This will help your marketing/product teams to use these parameters properly in campaign. Click Continue.
If the response time is between 100 and 500 ms, we show it as ‘Slightly High’ and >500 ms is VERY HIGH. Its recommended to have response time less than 100ms.
How to use Content API in Campaigns
Once you have added and tested a Content API, you can use it to fetch data and use the response data in any campaigns.
Order matters: When using multiple Content APIs, arrange them sequentially if you plan to pass the response from one API as input to the next.