Regex Tester
Test JavaScript regular expressions live with match highlighting, capture groups and replace preview.
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Runs entirely in your browser — nothing is uploaded
How to use the Regex Tester
- 1
Enter a pattern and flags
JavaScript syntax, including named groups.
- 2
Paste test text
Matches highlight instantly.
- 3
Inspect groups or replace
See each match’s captures.
Build and debug regular expressions against your own sample text. Matches are highlighted as you type, capture groups are listed for every match, and you can preview a replacement.
Read the full guide with screenshotsFrequently asked questions
Is the Regex Tester free?
Yes — completely free with no daily limit and no account. ZapMorph’s viewers and developer tools are unmetered.
Is what I type sent anywhere?
No. Everything runs in your browser with JavaScript. Nothing you enter is sent to our servers, which makes it safe for API keys, tokens and private data.
Does it work on my phone?
Yes. It works in any modern browser on iPhone, Android, Windows, Mac and Linux, with nothing to install.
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