Set it up in Slack and HipChat, or give it a try below:

/tz
↵  
  • 10:00 am CET in Stockholm is 5:00 am EDT for you
  • Stockholm is 5 hours ahead of you
  • 10:00 am KST in Seoul is 9:00 pm EDT the previous day for you
  • Seoul is 13 hours ahead of you
  • 10:00 am CET in Stockholm is 6:00 pm KST for Seoul
  • Stockholm is 8 hours behind Seoul

Examples: