Zoho One is a all-in-one suite to run your entire business. It includes CalDAV calendars and CardDAV contacts.
CalDAV Base URL:
https://calendar.zoho.eu/ (depending on where you have created the account)
CardDAV Base URL:
User name and pasword: your Zoho email address and password. If you're using two-factor authentication, you have to generate and use an application-specific password for DAVx⁵.
CardDAV: vCard contact groups are not supported. Choose the method used by your other clients or "per-contact categories" to minimize potential problems.
CardDAV: Contacts from the "Organization" address book are not provided via CardDAV and can't be synchronized.
CalDAV: VTODO tasks don't seem to be supported by Zoho.