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Regex Tester
Test regular expressions against sample text with live match highlighting and capture group breakdown.
🔒 Runs entirely in your browser — no data is ever sent anywherePattern
Flags
Test string
Frequently asked questions
What regex flavor does this tool use?
JavaScript's native regex engine (ECMAScript), the same one used by Node.js and every browser. Syntax and behavior may differ slightly from PCRE, Python, or .NET regex in edge cases like lookbehind support and Unicode property escapes.
Why isn't my pattern matching anything?
Common culprits: forgetting the 'g' flag when you expect multiple matches, unescaped special characters like '.' or '(' that need a backslash, or case sensitivity — add the 'i' flag for case-insensitive matching.
How do I see capture groups?
Capture groups — the parts of your pattern wrapped in parentheses — are broken out separately for each match, so you can see exactly what each group captured without manually counting parentheses.