Free tools
Regex Tester
Test regular expressions online — enter a pattern and flags, paste your test string, and instantly see all matches highlighted.
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Matches
Highlighted
Match list
No matches found.
Quick reference
. Any character \d Digit [0-9] \w Word char [a-zA-Z0-9_] \s Whitespace ^ Start of string $ End of string * Zero or more + One or more ? Zero or one {n,m} Between n and m (abc) Capture group a|b a or b [abc] Character class [^abc] Negated class \b Word boundary Flags:
g global i case-insensitive m multiline s dot-allRegex Tester Online
Enter a regular expression pattern and test string to instantly see all matches highlighted. The match list shows each match with its index position. Everything runs in your browser — no server involved.
How to use this tool
- Type your regex pattern in the pattern field (without the surrounding slashes).
- Add any flags in the flags field —
gfor global (find all matches),ifor case-insensitive,mfor multiline. - Paste or type the text you want to test in the test string area.
- Matches are highlighted and listed instantly.
Common regex patterns
- Email:
\b[\w.+-]+@[\w-]+\.[a-z]{2,}\b - URL:
https?://[^\s]+ - IPv4:
\b\d{1,3}(\.\d{1,3}){3}\b - Digits only:
^\d+$ - Phone (UK):
(\+44|0)[\d\s]{9,10}
Frequently Asked Questions
What is a regular expression?
A regular expression (regex or regexp) is a sequence of characters that defines a search pattern. It's used for string matching, searching, and manipulation. Regex is supported by virtually all programming languages, text editors, and command-line tools.
How do I test a regex pattern?
Enter your regex pattern in the pattern field, select any flags (modifiers) you need, then paste your test text in the input field. The tool instantly highlights all matches and shows match details including captured groups.
What regex flags are supported?
Common flags include: g (global — find all matches, not just the first), i (ignore case), m (multiline — ^ and $ match line start/end), s (dotall — . matches newlines), and u (unicode). The available flags depend on your target regex engine.
What are some common regex patterns?
Common patterns:
^\d+$ (numbers only), ^[a-zA-Z0-9]+$ (alphanumeric), \b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b (email), https?://\S+ (URLs), \d{4}-\d{2}-\d{2} (dates like 2024-01-15).Why isn't my regex working?
Common issues: forgetting to escape special characters like
., *, or + when you mean them literally; incorrect character classes; missing flags like i for case-insensitive matching; or using features not supported by your target regex flavor.Is this tool secure?
Yes. All regex processing happens entirely in your browser using JavaScript's RegExp engine. Your patterns and test text are never sent to any server. For sensitive data you're pattern-matching, this local processing ensures privacy.