Regex library - A curated list of most commonly used regular expressions with code examples in different programming languages: JavaScript, Python, Java, C#, and PHP.
i Hate Regex - regex cheatsheet for the haters
UI Bakery - An intuitive visual internal tool builder. Allows you to create admin panels, CRMs, customer support tools on top of your database. Integration with MySQL, PostgreSQL, MongoDB, and more. Add business logic, manage user permissions, share your app.
RegexLearn - RegexLearn makes it simple to learn, practice, test, and share RegEx.
Regex Crossword - Welcome to the fantastic world of nerdy regex fun!
RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.