Regex101

Regex101 is the go-to online playground for building and debugging regular expressions. As you type a pattern, it highlights matches in your test string in real time and explains each token, so you can understand exactly what your regex is doing.

It supports multiple regex flavors including PCRE, JavaScript, Python, and Go, and includes a quick reference, code generator, and the ability to save and share your patterns. It is completely free and indispensable for anyone learning or working with regex.