Text Diff Checker
Compare two texts online and see added and removed lines highlighted.
Regex Tester
Enter a pattern and test text below. Matches are highlighted live as you type, with capture groups listed for each match. Uses your browser's native JavaScript regex engine.
Private by default: processing stays on your device
YOUR REGEX
Pattern, flags, and test text
See every match live.
Highlights update as you type, with capture groups below.
Matches
Capture groups
Good to know
Live preview is bounded for safety: patterns over 500 characters and inputs over 20,000 characters skip highlighting, and each scan stops after 300ms. Everything runs in your browser.
Example: extract years
Input
Pattern: \b(19|20)\d{2}\b
Text: Born 1991, graduated 2013.Output
2 matches: 1991, 2013These buttons share the page link, not your input.
Want to include your text?
Your current input will be stored in the link after the # symbol, not uploaded to Handy Browser Tools. Anyone with this link can read that text. If you send or post it, the service you choose also receives the link. Do not include passwords or private information.
Frequently asked questions
Which regex flavor does this use?
JavaScript (ECMAScript), the same engine your browser runs. Most patterns behave like PCRE, but lookbehind and some Unicode features vary by flavor.
What do the flags mean?
g finds all matches instead of the first, i ignores case, m makes ^ and $ match line starts/ends, s lets . match newlines, u enables full Unicode mode.
Why does my pattern show an error?
The pattern isn't valid JavaScript regex syntax. The exact engine error is shown so you can fix it. Remember to escape special characters like . ( ) [ ] with a backslash.
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