Test and debug regular expressions
Enter a regex pattern, paste test text, and see matches highlighted in real time with capture groups.
Regex Pattern
Enter a regular expression and test text to see matches in real time.
2 matches
Matches highlighted below.
Invalid addresses: not-an-email, @missing.com, also missing@.com
| # | Match | Index |
|---|---|---|
| 1 | support@vultio.cloud | 14–34 |
| 2 | sales@vultio.cloud | 38–56 |
Why this tool exists
Vultio Regex Tester lets you write, test, and debug regular expressions in real time with match highlighting, capture group detail, and plain-English token explanations.
It supports all JavaScript regex flags and includes a Quick Reference panel with clickable tokens you can insert directly into your pattern — useful when you need to build a regex from scratch.
Common use cases
- Test an email validation regex against a list of real and malformed addresses.
- Debug a date-matching pattern by trying different input formats and seeing what gets captured.
- Inspect capture groups from a log-parsing regex before using it in production.
- Learn how a regex works by checking the Explanation panel token by token.
- Quickly verify that a URL-matching pattern does not accidentally match internal routes.
Example input / output
Email validation regex
Input
Output
Extract capture groups
Input
Output
Common errors
Invalid regular expression: ...
Cause: The pattern contains a syntax error — unmatched brackets, unescaped special characters, or an invalid quantifier.
Fix: Check the error message for the position of the issue. Common fixes: escape literal dots as \. and wrap character classes in [].
No matches found.
Cause: The pattern is valid but does not match any part of the test text.
Fix: Double-check the pattern against your test text. Try enabling the i flag for case-insensitive matching, or the g flag to find all occurrences.
Related guides
How to test regular expressions online, use flags, read capture groups, and common regex patterns for email, URL, and date matching.
A comprehensive guide to online regex testing, metacharacters, flags, and debugging strategies.
Standards & references
The complete reference for JavaScript regular expression syntax, flags, character classes, quantifiers, and groups.
An in-depth tutorial covering regex syntax across all major engines including JavaScript, Python, and PCRE.
Related tools
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Format raw JSON to make it easier to inspect.
Frequently asked questions
What is a regex tester online?
A regex tester lets you write a regular expression and immediately see which parts of your test text it matches, including capture group values and match positions.
Which regex flags are supported?
The tester supports the standard JavaScript regex flags: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky). Toggle them with the flag buttons.
What does the Explanation panel show?
It breaks your regex into tokens and explains each one in plain English — for example, \d+ is explained as "one or more digit characters".
Can I see capture group values?
Yes. The match table shows each match with its full value, all numbered capture groups, and the start and end index in the test string.
Is my regex or test text sent to a server?
No. All matching runs client-side using the browser's native JavaScript RegExp engine. Nothing is transmitted anywhere.