Regex Tester & Debugger
Test JavaScript regular expressions, inspect numbered and named capture groups, highlight matches, and preview replacements without sending text to a server.
Test a JavaScript regular expression
g finds every match; without it, only the first match is returned. Execution is stopped after 1.2 seconds to protect the page from runaway patterns.
Waiting for a pattern
Matches and replacement
Inspect every numbered and named group without logging source text.
Patterns run in a disposable Worker and are stopped before they can freeze the page.
Test JavaScript replacement tokens before using a pattern in code or data cleanup.
Test and debug JavaScript regular expressions
Enter a regex pattern, select global, case-insensitive, multiline, dot-all, or Unicode flags, and run it against up to 100,000 characters of test text. Matches are highlighted with their exact indexes and capture groups.
Use the replacement preview to verify numbered captures such as $1, the full match with $&, or named captures such as $<name>. Evaluation runs locally in an isolated browser Worker with a strict timeout.