The Acuity Scheduling Shell Sample Code by Acuity Scheduling allows to get started with the API to implement scheduling features into applications. Additional integration resources include OAuth2, webhooks, and CSS customization.
The Internet runs on standards. Without standards, we wouldn't have the Domain Name System (DNS) which resolves hostnames to Internet Protocol (IP) addresses, or the HyperText Transfer Protocol (HTTP) which served up this very web page. Even web service APIs, which can vary wildly depending on the back-end service, depend on standards like XML and JSON to make third-party development possible. And now, the W3C is jumping into the fray with a Working Draft for a general webapp Push API.