Regex Tester
Test, validate, and debug regular expressions in real time. Runs completely client-side for 100% data privacy.
Regex Tester
Test, validate, and debug regular expressions in real time. Runs completely client-side for 100% data privacy.
Regular Expression
0 charsExpression Modifiers (Flags)
Test String
0 chars • 1 linesMatch Results
0 MatchesNo matches found
Your pattern did not match any text in the test input. Adjust flags or edit pattern.
Token Explanation
Explanation pending
Write a regular expression pattern above to view a detailed breakdown of its elements.
How to Test Expressions
- 1Input Expression
Type your regular expression inside the top pattern field (delimiters `/` are visual only).
- 2Select Modifiers
Click modifiers pill buttons (Global, Case-insensitive) to set match parameters.
- 3Paste Test String
Fill the Test String panel with data. Highlights and sub-group captures refresh instantly on keypress.
Common Tokens Cheatsheet
\dMatches any numeric digit (0-9).\wMatches letters, digits, or underscore.\bMatches boundary between word & non-word..Matches any character except newline.+Matches 1 or more times (greedy).*Matches 0 or more times (greedy).Frequently Asked Questions
What is the Regex Tester?
It is a real-time regular expression editor and debugger that highlights pattern matches in your sample text.
Which regex engine does this tool use?
It uses the native JavaScript Regular Expression engine supported by your web browser.
Does this tester support standard flags?
Yes. You can toggle common flags like Global (g), Case-Insensitive (i), and Multiline (m).
Is my test text secure?
Yes. All pattern matching and text evaluations run in your browser, and no input data is sent to external servers.
How do I view captured groups?
Matched patterns and capture groups are highlighted in the results pane, showing character index positions.
What happens if my regex has a syntax error?
The tool detects invalid syntax and displays a clear error warning instead of crashing the editor.
Can I test lookarounds and backreferences?
Yes. The browser's modern JS regex engine supports lookahead, lookbehind, and backreference patterns.
What is a common regex mistake?
A common mistake is forgetting to escape special regex characters (like `.`, `*`, `?`, `+`) when matching literal strings.