Which regex flavor is used?

JavaScript (ECMAScript) syntax, matching front-end behavior and close to most languages' common usage.

Will many matches slow it down?

Match count is capped for safety; huge inputs or catastrophic backtracking can be slow, so debug on a small sample first.

Are my files or data uploaded?

No. Everything runs locally in your browser with no network upload, and is discarded when you close the page.

Do I need to sign up or pay?

No. The site is completely free, needs no account and has no usage limits.

🔍

🔍Regex Tester - Online Regular Expression Match & Highlight

Test JavaScript regular expressions live: enter a pattern and a test string to instantly highlight every match and list each match's capture groups. Supports the g, i, m, s and u flags. Everything runs in your browser for fast debugging.

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How to use Regex Tester

1Enter a pattern and tick the flags you need
2Paste text into the test box
3See highlighted matches and their groups

FAQ

Which regex flavor is used?: JavaScript (ECMAScript) syntax, matching front-end behavior and close to most languages' common usage.
Will many matches slow it down?: Match count is capped for safety; huge inputs or catastrophic backtracking can be slow, so debug on a small sample first.
Are my files or data uploaded?: No. Everything runs locally in your browser with no network upload, and is discarded when you close the page.
Do I need to sign up or pay?: No. The site is completely free, needs no account and has no usage limits.