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Regex Tester

Test regular expressions live with plain-english explanations, a mistake detector, a 12-pattern library and find-and-replace. Free and private.

Regex Tester - Test, Understand and Perfect Regular Expressions Live

Type a pattern, see every match highlighted instantly, and get a plain-English explanation of what each symbol does. Includes a mistake detector, a backtracking danger guard, a 12-pattern starter library, find-and-replace preview and shareable links. Everything runs on your device - your patterns never leave this page.

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100% private - patterns never leave this page Live results - matching happens as you type Plain-english explanations for every symbol
1

Pick or write a pattern

Start from the library - email, URL, date and more - or type your own. New to regex? The library is the easy way in.

2

Test it live

Matches highlight as you type. The breakdown panel explains every symbol in plain words.

3

Fix, replace, share

The mistake detector catches classic errors, replace preview shows your find-and-replace, and share links send the whole setup.

Pattern

//
finds all matches

Test Text

2 matches - 0ms
Contact john@example.com or support@toolkit.io for help.

Share this test

The whole setup - pattern, flags and test text - is encoded into a link. No account, no server, nothing saved.

Matches

0ms
Match 1
at position 8

john@example.com

Match 2
at position 28

support@toolkit.io

\wany word character (letters, digits, underscore)
+the previous piece repeats 1 or more times
@the exact text "@"
\wany word character (letters, digits, underscore)
+the previous piece repeats 1 or more times
\.the literal character "."
\wany word character (letters, digits, underscore)
+the previous piece repeats 1 or more times

Improve your pattern

No anchors found: this pattern can match in the middle of other words.

Add ^ at the start and $ at the end to match whole text, or \b on both sides to match whole words.

How to Use the Regex Tester

Getting Started

  • Open the Common Patterns Library and click Email or URL - the pattern and test text fill themselves.
  • Edit the pattern and watch matches highlight live in the text preview.
  • Toggle flags like i (ignore case) and g (find all) and see the match count change.
  • Your work auto-saves in this browser - refreshing keeps it.

Premium Help

  • The Plain-English Breakdown explains every symbol - no more guessing what \\d means.
  • The Improve panel warns about classic mistakes and dangerous patterns.
  • Find & Replace tests substitutions with $1, $2 group references.
  • Copy a share link to send the entire test setup to a friend - no account needed.
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