Regex Debugger & Visualizer

Debug regular expressions with step-by-step match visualization, pattern explanation, code generation, and substitution. Everything runs in your browser.

Regular Expression

/ /

Test String

Pattern Breakdown

Replace Matches

Use $1, $2, etc. for capture group backreferences. $& for full match. $<name> for named groups.

Result

Substitution result will appear here...

Generate Code Snippet

Common Patterns Library

.	Any character (except newline)
\d	Digit [0-9]
\D	Not a digit
\w	Word char [a-zA-Z0-9_]
\W	Not a word char
\s	Whitespace
\S	Not whitespace
[abc]	Any of a, b, or c
[^abc]	Not a, b, or c
[a-z]	Range: a to z

*	0 or more
+	1 or more
?	0 or 1 (optional)
{n}	Exactly n times
{n,}	n or more times
{n,m}	Between n and m
*?	0 or more (lazy)
+?	1 or more (lazy)

(abc)	Capture group
(?:abc)	Non-capturing group
(?<n>abc)	Named group "n"
\1	Backreference to group 1
(?=abc)	Positive lookahead
(?!abc)	Negative lookahead
(?<=abc)	Positive lookbehind
(?<!abc)	Negative lookbehind
a\|b	Alternation (a or b)

^	Start of string/line
$	End of string/line
\b	Word boundary
\B	Not a word boundary

g	Global (find all matches)
i	Case-insensitive
m	Multiline (^ $ per line)
s	Dotall (. matches \n)
u	Unicode support

Regex Debugger & Visualizer

Related Tools

Regex Tester

Diff Checker

Text Case Converter

JSON Formatter

Frequently Asked Questions