Regex visualiser

You should use editpadpro to write / test regexes

also this tool looks good: https://regexr.com/

This will draw them:

http://jex.im/regulex/#!embed=false&flags=&re=%5Ba-z0-9!%23%24%25%26'*%2B%2F%3D%3F%5E_%60%7B%7C%7D~-%5Cu00E0-%5Cu00FC%5D%2B(%3F%3A%5C%5C.%5Ba-z0-9!%23%24%25%26'*%2B%2F%3D%3F%5E_%60%7B%7C%7D~-%5Cu00E0-%5Cu00FC%5D%2B)*%40(%3F%3A%5Ba-z0-9%5D(%3F%3A%5Ba-z0-9-%5D*%5Ba-z0-9%5D)%3F%5C%5C.)%2B(%3F%3A%5Ba-z%5D%7B2%2C64%7D)

Here are some more links:

https://www.regexpal.com/95029
https://www.regexpal.com/
https://emailregex.com/regex-visual-tester/index.html
https://emailregex.com/
https://jex.im/regulex/#!flags=&re=%5B%5EA-Fa-e0-9%5D

Here is the official w3c regex to test for email address valid: 

(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])