The Instances API is the primary API in Zesty.io, the Zesty.io Content manage is built on top of it. Instances API is responsible CRUD on all instances related resources like content items, models, fields, files, settings etc.
Full documentation available in multiple programming languages an be found here https://instances-api.zesty.org/
Node Wrapper: Currently used in Cloud Functions, customer projects, and the ATOM Plugin https://atom.io/packages/zestyio-atom
NODE SDK: is a work in Progress