Free online tool
Regex Tester
Write a regular expression and see live matches in your sample text.
- hi@example.comat 14
- support@toolnest.devat 32
What regex is good at
Regular expressions describe patterns of text: an email address, a phone number, a date, or a snippet of code that starts a certain way. They're built into every major programming language and most text editors, so the pattern you write here works almost anywhere. The catch is that regex has a steep learning curve, and it's easy to write patterns that are subtly wrong.
Common flags
g finds all matches instead of stopping at the first. i makes matching case-insensitive. m lets ^ and $ match at line boundaries. s lets . match newlines. Combine them as needed — for example gim for a global, case-insensitive, multi-line match.
+Which regex flavor is this?
JavaScript (ECMAScript). Most patterns are portable, but lookbehinds and Unicode property escapes may differ in other languages.
+How do I match a literal dot?
Escape it with a backslash: \.
Why use the Regex Tester on ToolNest?
The Regex Tester is one of more than forty free browser-based utilities we maintain on ToolNest. Every tool on the site is engineered around the same three promises: it must be fast, it must protect your privacy, and it must be genuinely useful without hiding features behind an account, a paywall, or an email capture form. Whether you use the Regex Testeronce a month or several times a day, it should feel like a native part of your workflow — open the tab, get the result, move on.
Everything happens directly inside your web browser. When you type, paste, or upload something into the Regex Tester, that data never leaves your device. There is no server round-trip, no logging, no analytics pixel watching your keystrokes, and no third-party API silently receiving a copy of your input. Closing the browser tab is the same as clearing your session. This is a deliberate design choice: too many free "online tools" quietly funnel user content through remote servers, and we do not think a utility as small as this one justifies that risk.
Speed is the other pillar. The Regex Tester loads on a cold connection in well under a second and stays responsive on older phones, low-power laptops, and metered mobile networks. There are no heavy frameworks layered on top of the tool, no autoplay video ads, and no blocking third-party scripts. Search engines like Google reward pages that load quickly and stay interactive, but more importantly, so do human visitors who came here to get one specific job done.
If the Regex Tester saves you time, the best thing you can do is bookmark this page and share it with a colleague or classmate who might need it. We also welcome direct feedback — bug reports, feature requests, and suggestions for entirely new tools all go to the same inbox and are read by a human. The best tools on ToolNest started life as a one-line reader email, and this page will keep improving as long as people keep telling us what they wish it did better.