Full integration, editable calendar with two-way synchronisation – more complicated than it could be: https://frightanic.com/apple-mac/thunderbird-icloud-calendar-sync/.
For the sync of contacts, the URL is: https://<serverID>-contacts.icloud.com/<user>/carddavhome/card/. See: https://support.mozilla.org/bm/questions/1384897.
Read MoreWhen security risks in web services are discovered by independent security researchers who understand the severity of the risk, they often lack the channels to disclose them properly. As a result, security issues may be left unreported. security.txt defines a standard to help organizations define the process for security researchers to disclose security vulnerabilities securely: securitytxt.org.
Read MoreCreate and share meeting polls. With a meeting poll, an appointment can be made with several people. With a booking list, predefined appointments can be booked by other people: https://terminplaner6.dfn.de/.
Read MoreOn Nuudle, one can create polls to arrange an appointment or other simple surveys. In contrary to its sibling Doodle, Nuudle is fully anonymous, without any user-tracking, advertisement etc.: https://nuudel.digitalcourage.de.
Read MoreJustin Welsh is an experienced internet entrepreneur, meanwhile offering boutique advisory services for other entrepreneurs. He compiled a list of tools he uses himselves: