Regex Tester
What it is: Regex: a set of rules to match or extract content from text (emails, phone numbers…) without writing lots of conditionals.
When to use: When validating input, extracting in bulk, or doing find-and-replace on text.
Learn more about regex
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Everything runs locally in your browser — nothing is uploaded.
FAQ
Why is my regex slow or even hanging?
Some patterns (such as nested quantifiers like (a+)+) can trigger "catastrophic backtracking" (ReDoS) on certain inputs, causing runtime to explode. This tool runs the regex in a separate thread with timeout protection — if it times out you get a warning and the page never freezes.
Is the regex syntax here the same as in my language?
This tool uses the browser's JavaScript regex engine. Most syntax is shared with PCRE/Python, but a few features (such as certain lookarounds or \p{} properties) differ slightly across languages — for complex cases, always test in your target language.