Free Regex Tester Online

How to use

1. 1

   Enter your regex pattern

   Type your regular expression pattern and optionally set flags (g, i, m, s).

2. 2

   Paste your test string

   Enter the text you want to match against.

3. 3

   See matches highlighted live

   Matches are highlighted in real-time as you type.

Why use this tool?

• ✓Live highlighting updates as you type - no button needed
• ✓Runs in your browser, so your test data stays private
• ✓Shows match details including index, captured groups, and named groups
• ✓Limits output to 1000 matches to prevent browser freeze on pathological patterns

Frequently asked questions

What regex flavour does this support?

JavaScript regex (ECMAScript). This covers the vast majority of common regex patterns and is compatible with JS, TypeScript, and many other languages.

What flags are supported?

g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and d (indices).

Why does it stop at 1000 matches?

Catastrophic backtracking with certain patterns against large inputs can freeze a browser tab. The 1000-match limit prevents this.

Does it support named capture groups?

Yes. Named groups (?<name>...) are shown in the match details.

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