Two tools developers use constantly: a regex tester to debug patterns and a text compare to see differences between two versions. Both run best in the browser—paste pattern and sample, or paste two texts, and get instant results.
A good regex tester highlights matches and groups and supports your engine’s flavor. A text compare shows line-by-line or character diff with highlights. Free online versions mean no install and quick access from any machine.
Use our Regex Tester and Text Compare for debugging and comparison—free developer tools.