Regex Tester
Test JavaScript regular expressions against your input live. Donfig highlights every match in the test text, lists each match with its position and capture groups (numeric and named), and supports an optional replace mode with $1/$2 backreferences. All six standard flags are toggleable: g (global), i (ignore case), m (multiline), s (dotall), u (unicode), y (sticky). The pattern compiles live; invalid patterns show the precise error. JavaScript flavor regex matches what you'd get in Node, the browser, or any V8 runtime — useful for debugging frontend logic, validation rules, or template parsing.
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Frequently asked
Which regex flavor is this?
JavaScript / ECMAScript regex via the browser's native RegExp. Lookbehinds (\?<=) and named capture groups (?<name>) are supported.
Why are matches still listed when I don't have the g flag?
Donfig adds the g flag internally for collection so the listing always shows every match. Your flags still apply to the actual RegExp behavior in your code.
Does this support PCRE / Python regex differences?
No — it's strict JavaScript. PCRE-only features (atomic groups, possessive quantifiers, conditionals) aren't supported in JS.