What is regular expressions 101?
Regex101.com is an interactive regular expression console that lets you debug your expressions in real-time. What this means is that you can build your expressions and see how it affects a live data set all in one screen at the same time.
Regex101.com lets us build expressions fast and debug along the way. We can paste in a set of data and then, through trial and error, build a expression that does what we want.
The tool was created by Firas Dib, with contributions from many other developers. It is said to be the largest regex testing service in the world.