Regex Tester

Test, debug, and understand regular expressions with real-time matching, visual breakdowns, and code generation for multiple languages.

Regex Flavor

Quick Patterns

Mode

Regular Expression

✓ Valid ✗ Invalid

/ /

g - Global i - Case insensitive m - Multiline s - Dotall u - Unicode

Error:

Test String

matches

Replace With

Use $1, $2, etc. for capture groups, $& for full match

Pattern Builder

Match Results

Match Details:

Split Results:

Replace Result:

Pattern Explanation

Code Generation

Performance

Execution time:

Pattern length:

Test string length:

Capture groups:

Character Classes

. - Any character except newline

\d - Digit (0-9)

\D - Not a digit

\w - Word character (a-z, A-Z, 0-9, _)

\W - Not a word character

\s - Whitespace

\S - Not whitespace

[abc] - Any of a, b, or c

[^abc] - Not a, b, or c

[a-z] - Character range

Quantifiers

* - 0 or more

+ - 1 or more

? - 0 or 1

{3} - Exactly 3

{3,} - 3 or more

{3,5} - 3 to 5

*? - 0 or more (lazy)

+? - 1 or more (lazy)

Anchors & Boundaries

^ - Start of string/line

$ - End of string/line

\b - Word boundary

\B - Not word boundary

\A - Start of string

\Z - End of string

Groups & Lookaround

(abc) - Capture group

(?:abc) - Non-capture group

(?<name>abc) - Named group

(?=abc) - Positive lookahead

(?!abc) - Negative lookahead

(?<=abc) - Positive lookbehind

(?<!abc) - Negative lookbehind

Special Characters

\n - Newline

\r - Carriage return

\t - Tab

\\ - Backslash

\. - Literal dot

\* - Literal asterisk

Flags

g - Global (all matches)

i - Case insensitive

m - Multiline mode

s - Dotall (. matches newlines)

u - Unicode support

y - Sticky mode