Managing calendars and booking appointments

I'm going to build an application in Laravel where the central focus is around managing bookings against resources (employees).

A merchant can set up an account, add any number of employees and clients are able to book time slots with the merchant if there is availability.

The merchants will be able to manage their availability using the calendar and have the ability to create or cancel client bookings. Likewise the clients also have the ability to create or cancel their bookings.

While I could build this functionality myself, I feel that it would be a better use of my time to consume some existing calendar management tool such as Google Calendar, Outlook, iCloud etc. The idea being that the application can hook into the merchants existing calendar system.

I've been doing some research and I've found one API which might make this process easier https://www.cronofy.com/

Does anyone have experience or tips they could share with regard to tackling a project like this?