Regex Tester
Test regular expressions against sample text live.
Test regular expressions against sample text live
0 matches
How to use it
- 1Type a pattern, or pick one of the common presets.
- 2Toggle flags like case-insensitive or multiline as needed.
- 3Type or paste a test string and watch matches highlight live, with capture groups listed below.
- 4Optionally add a replacement using $1, $2… to preview a find-and-replace.
Supported formats & limits
Works with standard syntax — no file size limit, since everything runs in your browser.
Example
The pattern [\w.+-]+@[\w-]+\.[a-zA-Z]{2,} with the “i” flag finds both email addresses in “Contact us at [email protected] or [email protected]” — try one of the common patterns to see it highlight matches live.
How it works
Your pattern and flags build a native JavaScript regular expression, tested against your string as you type. Matches are highlighted inline, and each one is listed below with any capture groups (named ones included) it produced — useful for checking a pattern before dropping it into code. The actual matching runs in a background worker rather than on the page itself, so a pattern with catastrophic backtracking gets cancelled with a warning instead of freezing the tab. Add a replacement with $1, $2, or $<name> to preview what .replace() would produce.