I found that somewhere else in this forum and had one of those, ‘does everyone else already know this’ moments. I spoke to another developer I work with and he gave me a sort of, ‘really, you’ve not done that yet’ look. ;-)
I’m using crm.zoho.com at the moment and then manually putting my reminders in Google Calendar. Works very well. Although I’m sure a native app from a CRM would clean up.