regex101

regex101 is a popular online regex debugger: write the pattern on the left, paste test strings on the right, watch matches highlight in real time, and read a natural-language breakdown of what every part of your pattern does. Regex is five minutes to write and two hours to understand — this tool compresses the two hours into ten seconds.

1. Paste your pattern and real sample data, then read the Explanation panel to confirm what each token means.
2. When matching goes wrong, open the debugger and step through to see where it derails.
3. Switch the flavor (JavaScript, Python, PCRE and more) when porting across languages — the same pattern can behave differently in each.
4. Generate a share link when you're done for your own archive.

• Live match highlighting — every character change reflects instantly
• Token-by-token plain-language explanations make reading other people's regex painless
• Flavor switching prevents porting surprises
• Step debugging and shareable permalinks cover both troubleshooting and archiving