Regex Tester
Test regular expressions against sample text. See matches and use replace. All processing runs in your browser.
Result
Regex Tester Tips
Flags
Use g for all matches, i for ignore case, m for multiline (^ and $ per line).
Escaping
In JavaScript regex, escape special characters like . * + ? [ ] ( ) with a backslash.
Capture Groups
Use parentheses ( ) for capture groups; they appear in the match result and in replace.
Privacy
All testing runs in your browser; your text and pattern are never sent to a server.
Secure & Private
Your regex and text are processed only in your browser.
Instant Results
See matches and replace results as you test.
Match & Replace
Test patterns and try replace with optional replacement text.
Completely Free
No signup, no limits.
Test Regular Expressions Online
Our regex tester lets you test and debug regular expressions against sample text. See matches, capture groups, and try replace—all in your browser. Perfect for developers validating input, parsing text, or building search patterns.
Need more developer tools? Try our web tools: JSON formatter, base64 converter, and hash generator.
How to Use the Regex Tester
Step 1: Enter pattern and text
Type your regular expression and the text you want to test against.
Step 2: Set flags
Enable g (global), i (ignore case), or m (multiline) as needed.
Step 3: Test and replace
Click Test to see matches. Optionally enter "Replace with" to see the replaced string.
FAQs About Regex Tester
Is the regex tester free?
Yes. The tool runs in your browser and does not send data to any server.
Which regex flavor is used?
JavaScript (ECMAScript) regular expressions. Syntax may differ slightly from Perl or other engines.
Can I use capture groups?
Yes. Parentheses create capture groups; they appear in the match list and can be used in replace (e.g. $1, $2).
Why do I get "Invalid regex"?
Unclosed brackets, invalid escapes, or unbalanced parentheses cause errors. Check your pattern syntax.
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Conclusion & CTA
Use our regex tester to debug patterns and try replace online—free and private.
