Enter a pattern, tick the g, i, m, s, u, and y flags you need, paste your test text, and the matches light up in the panel below. Invalid patterns are flagged inline as you type, so you can fix a stray bracket or escape without leaving the page, and each match is broken out with its position, length, and capture groups.
Regex Tester Online
Regular expressions are easy to get subtly wrong, and a pattern that looks correct can still miss the strings you actually care about. This tester runs your pattern against your own sample text right in the browser, so you can confirm exactly what it matches before you paste it into code. Type the pattern, tick the flags you need, and every match lights up in the panel below as you type, with invalid patterns flagged inline instead of failing silently.
Every match is broken out with its starting position, its length, and the contents of each numbered or named capture group, which makes it quick to see why a group came back empty or grabbed more than you expected. A starter library of common email, URL, IPv4, phone, and date patterns gives you a working expression to adapt instead of starting from a blank box. Nothing you type is uploaded; the matching runs entirely on your own device.
Frequently Asked Questions
What does Regex Tester Online do?
Test a regular expression against your own sample text and watch every match highlight as you type.
When should I reach for regex tester online?
Reach for it when a pattern is not catching what you expect and you want to confirm exactly which characters it matches before pasting it into code.
Are there starter patterns I can build from?
One-click starter patterns for email, URL, IPv4, phone, and date give you a working expression to adapt instead of beginning from a blank box.