Developer Tools
Regex Tester
Live highlighting, common patterns library
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Matches
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Quick guide
What can Regex Tester help you do?
Free online regex tester. Live match highlighting, supports g/i/m/s/u flags. Common patterns included.
Best for
Test JavaScript patterns before bulk edits, form checks, or log searches. Presets cover Email, Phone (TW), Taiwan ID, VAT Number, and URL.
How to use it
Enter Pattern, Flags such as g or i, and a Test String. The g flag finds every match; without g only the first appears. Presets fill examples.
How to read the result
Matches are highlighted with positions. Invalid input shows an error; test empty strings, spaces, and bad cases too.
Privacy and limits
RegExp runs locally. Never paste production logs, tokens, real passwords, email lists, or raw personal data.
Presets skip checksums and cannot prove an Email or URL exists. Heavy backtracking may freeze pages.
Frequently Asked Questions
Is this JavaScript regex?
Yes — ECMAScript engine. May differ slightly from Python/Perl regex.