Regex101
regex101.com
Real-time regex tester with explanation, debugger, and community library.
Regex101 provides an interactive environment to build, test, and debug regular expressions in real time. It explains each token in plain English, highlights matches visually, and includes a debugger that steps through the regex engine.
Why it is useful
The token-by-token explanation turns opaque regex into readable logic. The community library contains thousands of pre-built patterns for common tasks like email validation and URL parsing.