What are some alternatives?
When comparing World Time Buddy and Timezone.io, you can also consider the following products
timeanddate.com - Free Clock for your website or blog!
Spacetime - Work hour and time zone management for distributed teams.
Time.is - exact time in any location
FlagTimes - The macOS app for anyone working in multiple timezones.
Every Time Zone - Online tool for keeping up with times around the world.
Timezoner - Time zone calculator bot for Slack