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What is Regex Tester?
Regex Tester is a free online tool for building, testing, and debugging regular expressions (regex). Write your pattern, enter test text, and instantly see matches highlighted — with group captures, match positions, and plain-English explanations of what each part of your regex does. All matching runs locally with no server round-trip.
How to use Regex Tester
1
Enter your regex pattern (e.g., /[a-z]+@[a-z]+\.com/g)
2
Type or paste test text below
3
Matches highlight in real-time with group captures shown
4
Read the explanation panel to understand what each regex token does
Common use cases
- Building and testing validation patterns (email, phone, URL)
- Extracting data from logs and structured text
- Learning regex through interactive experimentation
- Debugging complex patterns with match highlighting
Frequently Asked Questions
What regex flavors are supported?
JavaScript regex (ECMAScript) — includes lookaheads, lookbehinds, named groups, and Unicode property escapes.
Can I test multiple patterns at once?
Yes — the tool highlights all matches simultaneously and shows individual group captures for each match.
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