Regex Tester is a small Android utility built around one job: type a pattern, paste some text, and see instantly what it matches. That workflow doesn’t need a phone screen or an install step, so we built a browser version of the same idea. Type a pattern on the left, paste your test string, and every match lights up as you type, with capture groups broken out below. Nothing you type leaves this page.
Test your regex now
Type a pattern, paste your test string, and matches highlight live. A small library of common patterns below the flags lets you load an example with one tap.
How to use it
Type or paste a pattern into the field at the top; the sample email pattern that loads by default shows the idea immediately, with matches highlighted in the test string below and a match count on the right. Toggle g (global, match everywhere instead of stopping at the first hit), i (ignore case), and m (multiline, so ^ and $ match the start and end of each line) as checkboxes next to the pattern. A green “Valid” badge confirms your pattern compiles; an invalid pattern switches to red and shows the exact error instead of breaking the page.
Tap any snippet chip (email, URL, phone, hex color, IPv4, date) to load a working pattern and a matching sample string in one go, so you can see how a pattern is built rather than starting from a blank field. The results panel lists every match with its position in the string and any capture groups it produced, numbered or named. “Copy” grabs the pattern text alone, a separate, private action that never opens a share menu. Your last pattern, flags, and test string are saved on your device and reload automatically next time you visit.
How it compares to Regex Tester
The web version keeps the core loop of the Android app: type a pattern, see it matched against real text immediately, with no “run” button and no separate compile step. That live feedback loop is the entire reason a regex tester is useful, so it was the first thing we built and the last thing we’d cut.
The full Regex Tester app goes further. It keeps a history of patterns you’ve tested, supports saving favorites for reuse across projects, and is built to fit into a longer working session on your phone where you’re testing patterns against real data you already have open elsewhere on the device.
We left out history and saved favorites here on purpose. A browser tab is disposable by nature, and this page is built for the moment you need to check a pattern right now, from whatever device you’re on, without opening an app or creating an account. For a quick sanity check on a regex before you paste it into code, this page is faster. For a pattern library you build up over weeks of regular work, install the app.
Get the full app
Regex Tester is free on Android, with saved pattern history and favorites for developers who test regular expressions often enough to want them close at hand.
Frequently asked questions
Can I test regex online for free?
Yes. This page runs entirely in your browser. Type a pattern and a test string and matches highlight live, with no install and no account required.
Is my text sent anywhere?
No. Everything runs client-side in your browser. Your pattern and test string are matched locally by your browser’s own regex engine, and nothing you type is transmitted anywhere or stored on any server. The only place your data is saved is your own device’s local storage, so it survives a refresh but never leaves your browser.
Does it support standard JS/PCRE-style regex syntax?
Yes. It uses the JavaScript regular expression engine built into your browser, which covers the syntax most developers already know: character classes, quantifiers, anchors, capture groups, named groups, and lookahead. A pattern that works in a JavaScript codebase will behave the same way here.
Does it work offline?
Yes. Once the page has loaded, matching keeps working without a connection, since the matching happens entirely on your device.
Is this the official Regex Tester app?
No. This is an original tool we built, inspired by the quick type-and-match job that Regex Tester does well on Android. It is not affiliated with, endorsed by, or connected to its developer. For pattern history and saved favorites, get the official app above.
