Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Time.is - exact time in any location
Itsycal - Itsycal for Mac. Itsycal is a tiny menu bar calendar. If you want, it will display your events as a companion to the Mac Calendar app. You can also create and delete (but not edit) events. Download Itsycal for macOS 10.
Every Time Zone - Online tool for keeping up with times around the world.
BusyCal - powerful calendar app for macOS
timeanddate.com - Free Clock for your website or blog!