Regex Tester Online

Test JavaScript regular expressions and inspect matches, capture groups and character positions. Free regex tester online, with no installation or account.

Tool capabilities

Input: TXT
Output: JSON · TXT

How to use Regex Tester

Test JavaScript regular expressions against sample text and inspect match offsets, numbered captures and named capture groups.

Enter the pattern without surrounding slash delimiters.
Choose flags such as g for all matches, i for case-insensitive matching or m for multiline anchors.
Run the expression and inspect the JSON match list. Edit the pattern or text to test another case.

Regex Tester · Example

Input

Hello LocalKit. Small tools, useful results.

Output

{
  "matches": [
    {
      "text": "Hello",
      "index": 0,
      "captures": [],
      "groups": {}
    },
    {
      "text": "Small",
      "index": 16,
      "captures": [],
      "groups": {}
    }
  ],
  "displayLimit": 1000,
  "limitReached": false
}

Usage notes

Offsets count JavaScript UTF-16 code units. Unicode characters can occupy more than one code unit.

A two-second deadline terminates expensive patterns. At most 1,000 matches are displayed for inputs of up to 100,000 characters.

JavaScript regular expression syntax can differ from PCRE, Python and other regex engines.

Regex Tester