Adding a domain you own to your DigitalOcean account lets you manage the domain’s DNS records with the control panel and API. Domains you manage on DigitalOcean also integrate with DigitalOcean Load Balancers and Spaces to streamline automatic SSL certificate management.
The DigitalOcean API lets you manage DigitalOcean resources programmatically using conventional HTTP requests. All the functionality available in the DigitalOcean Control Panel is also available through the API.
doctl is a command-line interface for the DigitalOcean API and supports many of the same actions.