Regular Expression Tester Online

Test regular expressions with real-time match highlighting, capture groups, and a library of common patterns for email, URL, IP, and more.

Pattern Library

How to Use

  1. 1

    Enter pattern

    Type your regex pattern and optional flags (g, i, m).

  2. 2

    Add test text

    Enter sample text. Matches highlight instantly as you type.

  3. 3

    Browse patterns

    Load common patterns like email, URL, IP, or phone validation from the library.

FAQ

How do I match a space in regex?

Use \s to match any whitespace (space, tab, newline) or a literal space character. \S matches non-whitespace. For only spaces (not tabs/newlines), use the literal space character or [ ] in a character class.

What is a regex wildcard?

The dot (.) is the regex wildcard — it matches any single character except newline. Use .* to match zero or more of any character. Use [\s\S]* to match anything including newlines.

How do I handle special characters in regex?

Escape special regex characters with a backslash: \. \* \+ \? \( \) \[ \] \{ \} \^ \$ \| \\. Inside character classes [], most specials lose their meaning except ] \ ^ -.

What is a negative lookahead?

Negative lookahead (?!pattern) asserts that what follows does NOT match the pattern. Example: foo(?!bar) matches "foo" only when NOT followed by "bar". It is zero-width (consumes no characters).

How do I make regex case insensitive?

Add the "i" flag to your regex: /pattern/i in JavaScript. In this tool, type "i" in the flags field. This makes [a-z] also match uppercase letters and vice versa.