Timezone.io - Keep track where and when your team is.
Time Buddy - Time Buddy brings a colorful world clock.
Spacetime - Work hour and time zone management for distributed teams.
Time Zone Converter - Time Zone Converter is an online productivity tool to calculate exact time across time zones.
TimeLord for Slack - Timezone converter bot for Slack
World Clock - World Clock is an app that lets you see the time of any city in the world.