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Regex Tester

Test a regular expression and see every match with its groups.

Regular expressions can backtrack catastrophically. This page caps the input at 20,000 characters, but a pathological pattern can still lock the tab. If that happens, reload without your pattern.
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Matches

Matches

0

Capture groups

0

Test string length

0

Coverage

0%

Match details

#MatchIndexGroups

Common patterns

Flags: g find every match, i ignore case, m multiline anchors, s dot matches newlines, u Unicode mode. Without g only the first match is reported, which is the correct behaviour for a single search.

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What Is Regex Tester?

The Regex Tester runs a regular expression against your test string, highlights every match in place, and lists each match with its index and capture groups. Flags for global, ignore case, multiline, dot all, and Unicode are one click away.

Who Uses the Regex Tester?

Developers use it to check a pattern before shipping it, and to understand what a regex they did not write is actually capturing. Common patterns for email, URL, IPv4, colour, and phone number are included.

How to Use the Regex Tester

  1. Type your pattern between the slashes.
  2. Toggle the flags you need.
  3. Paste your test string and read the highlighted matches.

Why Choose Our Regex Tester?

  • In-place highlighting of every match
  • Capture groups per match, not just the full match
  • Eight common patterns one click away

Try the Regex Tester above — it is free, fast, and works on any device. Bookmark this page to return whenever you need it.