Text ToolsGuide 3 min read
How to Test Regular Expressions
Test and debug JavaScript regex against sample text, with flags and live match results.
June 3, 2026
Regex Tester — free, no sign-up
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How to Test a Regex
Step 1: Open the Regex Tester Go to the Kinsutools Regex Tester.
Step 2: Enter your pattern and flags Type the regular expression in the pattern field and add flags like g (global), i (case-insensitive), m (multiline) or u (unicode).
Step 3: Add sample text Paste the text you want to match against. Matches and their positions appear instantly.
Common Flags Explained
- g — find all matches, not just the first
- i — ignore upper/lower case
- m — treat each line as a separate start/end
- u — full unicode support
Tips
- It uses JavaScript regex, the same engine as browsers and Node.js.
- If your pattern is invalid, you'll see the error message instead of matches.
- Escape special characters like . * + ? ( ) [ ] when you want them matched literally.