Free Regex Tester
Test regular expressions in real time with match highlighting, capture groups, and flag support.
Free, no signup — enter a pattern and test string to find matches instantly. Supports IGNORECASE, MULTILINE, DOTALL, and VERBOSE flags, evaluated securely in your browser.
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How to Test a Regex Online
Go from a raw pattern to highlighted matches in three quick steps.
Enter Your Pattern
Type or paste a regular expression — for example an email, phone, or URL pattern — into the pattern field.
Add a Test String & Flags
Paste the text to test against and toggle IGNORECASE, MULTILINE, DOTALL, or VERBOSE flags as needed.
Inspect Matches
See every match highlighted with its position span and numbered or named capture groups, in real time.
// pattern
(\w+)@(\w+)\.com
// test string
contact jane@acme.com
group 1: jane · group 2: acme
Real-time Matching
Test your regex patterns instantly and see all matches highlighted with their position spans.
Capture Groups
View numbered and named capture groups for each match to debug complex regex patterns.
Regex Flags
Toggle IGNORECASE, MULTILINE, DOTALL, and VERBOSE flags to match the exact behavior you need.
Frequently Asked Questions
What is a regular expression?
A regular expression (regex) is a pattern used to match character combinations in strings. It's used in text search, validation, and data extraction across programming languages like Python, JavaScript, and many others.
What does the IGNORECASE flag do?
The IGNORECASE (re.I) flag makes the pattern match letters regardless of case. For example, the pattern hello would match "Hello", "HELLO", or "hElLo".
What is a capture group?
Capture groups are parts of a regex enclosed in parentheses (). They let you extract specific portions of a match. Named groups use the (?P<name>pattern) syntax so you can reference matches by name.
Why isn't my regex matching anything?
Common causes are unescaped special characters (like . + * ? ( )), the wrong flags, or anchors such as ^ and $ that are too strict. Test your pattern here with match highlighting to see exactly what does and doesn't match.
Is the Regex Tester free and private?
Yes. It is completely free with no signup, and your pattern and test string are evaluated in the browser — nothing is uploaded or stored.
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