Zendesk API Client by ZendeskOfficially supported
Zendesk2 by Joshua LaneSupported by the developer

Zendesk API Client by Zendesk

Zendesk maintains an official Ruby API client. You can use the client in a project by simply including the zendesk_api gem.

Zendesk2 by Joshua Lane

Zendesk2 is an API client developed by Joshua Lane. You can use it in a project by adding the zendesk2 gem to your application's Gemfile.