This is a simple app which shows a clock in one of the corners of the screen. The clock can be toggled by tapping it. It features a variety of customization options including timezone title date/time formats and more.

About custom date formats:
The following tokens can be used:
d - day
E - day of the week
M - month
y - year

'dd' 'MM' 'yy' use double digits for their values (e.g. 05 for 5)
'MMM' 'EEE' show shorthand names (e.g. Dec Jan Wed Fri)
'MMMM' 'EEEE' show full names (e.g. December January Wednesday Friday)
'yyyy' shows the year in 4 digits

You can mix these with symbols as well.
Using 5th December 2017 here are some examles:
dd-MM : 05-12
dMMMyy : 5Dec17
dd-MM-yyyy EEE: 05-12-2017 Tue
dd/MM EEEE: 05/12 Tuesday