Toolbox for developers / Online Regular expression tester

Regex Tester

Regular expression to test
String to test



This online tool allows you to test regular expression in JavaScript and PCRE (PHP).

You can consult the regex Quick Start or see the full user guide to help you to use this regular expression tester.

User guide

  • Step 0: Choose the regex engine: JavaScript or PCRE / PHP.
  • Step 1: Copy and paste or directly type your regular expression to test in the "Regular expression to test" field.
  • Step 2: Select the flags you want in "Flags" section.
  • Step 3: Copy and paste or directly type your test string in the "test string" field.
  • As soon as you make a modification (regular expression, flags or test string):
    • Step 4: An explanation is generated about of your regex. It uses regulex, it is a JavaScript Regular Expression Parser & Visualizer (Written in pure JavaScript).
    • Step 5: A message indicates the number of correspondence
    • Your regex is highlighted according to the syntax. It is a beta version, it can be wrong.

    regex tester user guide

  • You can also replace regular expression matches in text with a replacement string.

    Step 6: Copy and paste or directly type your substitute string in the "Substitution" field.

    Step 7: Substitutions are automatically performed on your test string.

    regex tester user guide

  • You can save your regex in order to share it. You can protect your share with a password, so only you can change it. See "Save and Share" section:

    share regex tester

  • Substitutions are not managed.

    The unavoidables

    Some regex that can be useful (without warranty).

    Email address

    The last RFC is complex, there is no reliable solution, this regex should work more than 99% of the time (You must turn off case sensitivity).



    The regex below allows to validate alphanumeric string. Be careful, \w authorizes the underscore character.



    The regex below allows to validate MD5 string.


    IP V4

    The regex below allows to validate IP v4.


    About regular expression

    A regular expression is a sequence of characters that define a search pattern. This pattern is used by string searching algorithms for find or replace text.

    It can be useful to validate an EMAIL address or an IP address.

    Regular expression tester

    This tool is an online regex checker, it allows to easily test and debug regex. This avoids wasting time writing the few lines of code needed to do the tests.

    This tool also allows you to share your regular expressions, this can be useful when you want to explain one of your regex problems (or its resolution) on a forum.

    RegEx Engine
    Save and Share
    Save this regular expression in order to share it.
    Be careful, the data will be accessible to everyone, please do not save sensitive data.
    Quick Start
    $End of string or end of line (in multi-line pattern)
    ^Start of string or start of line (in multi-line pattern)
    \bWord boundary
    \BNot word boundary
    x?0 or 1
    x+1 or more
    *0 or more
    {2}Exactly 2
    {2,}2 or more
    {2,5}Between 2 and 5
    .Any single character except line break (\n, \r)
    \wWord character
    \WNon-word character
    \DNon-digit character
    \sWhitespace character ([ \f\n\r\t\v\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
    \SNon-whitespace character
    \bBeginning/end of a word
    \BNot at the beginning/end of a word
    \nNew line character
    \rCarriage return character
    \tTab character
    \vVertical tab character
    \0NUL character
    \fForm feed character
    \xxxCharacter specified by an octal number xxx
    \xddCharacter specified by an hexadecimal number dd
    \uddddUnicode character specified by an hexadecimal number dddd
    [xyz]Any character between the brackets
    [^xyz]Any character not between the brackets
    [x-z]Any character from x to z
    [^x-z]NOT (Any character from x to z)
    (x|y)Any of the alternatives specified
    Save regular expression
    Your regex has been permanently saved and you (or anybody) can access with this link:
    Choice a password to modify/delete this regex later Enter password to modify this regex. Enter password to delete this regex. Enter the new password for the fork.
    You can report a bug or give feedback by adding a comment (below) or by clicking "Contact me" link (at the top right hand corner of the page).


    Disclaimer: The tools are provided "as is", without warranty of any kind, either express or implied.
    Any links to third-party website or software available on this website are provided "as is",
    without warranty of any kind, either express or implied and are to be used at your own risk.