Regex

The gap between the pattern you meant and the pattern you typed is where the afternoon goes. Paste one in and it explains itself back to you, one token at a time.

Every piece of the expression gets named: this is a character class, this quantifier is greedy, this group captures and that one only looks. Type into the test string and matches light up as you go, each one broken out into a card showing the groups it caught. When the pattern does something surprising, the explanation usually tells you why before you have to reason it out.

Good for

• Working out why a pattern matches one line too many.
• Reading someone else’s regex without deciphering it character by character.
• Checking capture groups land where you think they do.
• Learning the syntax by watching a real pattern get taken apart.

Why it’s a speck

It does one job and runs entirely in your browser. Paste something in, read what it says, close the tab.

Open Regex