Plato - Share knowledge with your team through simple Q&A

rubular - A ruby based regular expression editor

SavvyCal - A scheduling tool both the sender and the recipient will love.

RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.

Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.

RegEx Generator - RegEx Generator is a simple-to-use application that comes with the brilliance of intuitive regex and is also helping you out to test the regex.