Test and debug regular expressions instantly with match highlighting, flags, and detailed results.
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Free Online Regex Tester
The Regex Tester is a free online tool that helps you test and debug regular expressions
directly in your browser. It is useful for developers, students, testers, and anyone working with text
validation, search patterns, input matching, log parsing, or text extraction.
Regular expressions are powerful pattern-matching tools used in programming, search and replace operations,
form validation, filters, parsers, and automation workflows. A regex tester makes it much easier to check
whether your pattern behaves exactly the way you expect.
This tool works directly in your browser, so your patterns and test text stay private and are not uploaded
to a server. Enter a regex pattern, add optional flags, paste your sample text, and instantly see matches,
counts, and highlighted output.
How to Use the Regex Tester
Enter your regular expression pattern in the pattern field.
Add optional flags such as g, i, or m.
Paste or type the text you want to test.
Click Test Regex to view matches, highlighted text, and match count.
Features of This Tool
Instant regex testing
Supports regex flags
Highlights matched text
Shows total match count
Lists matched values
Includes sample pattern and text
Runs fully in the browser
Free to use on desktop and mobile
Why Use a Regex Tester?
Regex can be powerful but also difficult to debug when a pattern is too broad, too narrow, or behaves
differently because of flags. A regex tester helps you quickly see which parts of a string are matched so
you can adjust your pattern faster.
It is especially useful for validating emails, numbers, dates, usernames, URLs, logs, IDs, codes, and
other structured text patterns used in development and data processing.
Frequently Asked Questions (FAQ)
A regex tester helps you test whether a regular expression pattern correctly matches
the text you want. It is commonly used for debugging validation rules, search patterns, and text
extraction logic.
Regex flags change how a pattern behaves. For example, g finds all matches,
i ignores case differences, and m enables multiline matching.
No. This tool works directly in your browser, so your test text and regex patterns are processed locally
and are not uploaded or stored on a server.
Yes. You can combine flags such as gi or gm depending on how you want
the regex to behave.
You may get an error if your pattern contains invalid syntax or unsupported flag combinations. Check
for missing brackets, invalid escapes, or duplicate flags.
Yes. The tool is completely free to use with no registration required.