What we do with your Google data
CalCollapse requests three Google scopes and no others. None of them can write anything to your Google account, and each is here because a specific part of the app stops working without it:
openidIdentifies the Google account you are connecting, so we can tell your connected accounts apart.https://www.googleapis.com/auth/userinfo.emailReads that account's email address, so the account is labelled with something you recognise rather than an opaque id.https://www.googleapis.com/auth/calendar.readonlyLists the calendars on the account, so you can choose which to sync, and reads the events on the ones you chose, so they can be copied to iCloud.
That is the whole of it. We request no scope that can write to Google, so nothing in your Google Calendar can be created, changed or deleted by this app even in principle — and we ask for nothing outside Calendar at all: no mail, no contacts, no files.
Your events are stored so that each run only has to fetch what changed since the last one. They are deleted when you delete the calendar pair, disconnect the account, or delete your account. We do not sell your personal information, and nothing in your calendar is used for advertising or shared with anyone else. The full detail is in the privacy policy.
You can withdraw the access at any time, either by disconnecting the account here or by removing CalCollapse from your Google account permissions.