I often need to schedule meetings with participants in multiple timezones. My favourite feature of time.is is the ability to easily assemble a link like https://time.is/1400_3_Jul_2020_in_London/CEST/Toronto using a mix of geographic locations and timezone abbreviations. If you co-ordinate across multiple timezones a lot, this website is very useful and has a number of handy shortcuts and customisations available.