calsync is a small personal tool that keeps the owner's own Google Calendar and iCloud calendars in sync with each other.
It is built and used by one person for their own calendars. It is not offered to the public, has no accounts or sign-up, and does not collect data from visitors to this page.
To read Google Calendar events, the app asks for access to the owner's Google Calendar and uses that access only to copy, update and delete the owner's own events between the owner's own calendars.