Test regular expressions against sample text with real-time match highlighting and a built-in cheatsheet.
Developers validating input patterns before wiring them into backend validation logic.
Enter your regex pattern
Type or paste your regular expression into the pattern field, and set flags like g, i, or m.
Paste your test string
Add the sample text you want to match against — the more representative of real data, the better.
Read the live results
Matches highlight as you type, and the match count and captured groups appear below so you can verify the pattern.
Regular expressions are powerful but unforgiving: a single misplaced quantifier or unescaped character changes what matches, and the bug often hides until it hits real data in production. Building a pattern blind — editing in your code, redeploying, and checking the logs — is painfully slow. What you actually need is a live sandbox where you can see, character by character, exactly what your pattern matches against real sample text. This tester gives you that instant feedback. Type a pattern and paste your test string, and matches highlight in real time, with a match count and any captured groups shown below so you can confirm your pattern does exactly what you intend before it touches your codebase. It uses the JavaScript (ECMAScript) regex engine and supports the common flags, plus one-click preset patterns for everyday cases like emails and URLs. Everything runs in your browser, so the text you test — which might include real user data — never leaves your device.
Input validation
Prove out email, phone, URL, and postcode patterns against good and bad examples before wiring them into validation logic.
Search & replace
Build and verify patterns for find/replace in editors, scripts, and data-cleaning pipelines.
Log & data parsing
Design capture groups that pull structured fields out of log lines, CSVs, and error messages.
Learning regex
Experiment safely and watch how each change to the pattern affects what matches — the fastest way to learn.
Debugging a failing pattern
Paste a regex that misbehaves in production and the data it should match to see exactly where it goes wrong.
JavaScript RegExp (ECMAScript). PCRE-only features such as lookbehind in older engines or recursion may not be available.
No. All matching runs in your browser, so your pattern and test text — including any real data — never leave your device.
The common ones: g (global), i (case-insensitive), m (multiline), and s (dotAll).
Yes. Along with the match count, it lists the captured groups so you can confirm your parentheses capture the right parts.
One-click presets for email, URL, phone number, IPv4 address, and common date formats to use as a starting point.
Use the m flag so ^ and $ match at line breaks, and the s flag if you need . to match newline characters too.
Common causes are forgetting the g flag, not escaping special characters like . or ?, or a case mismatch — add the i flag to test.
Yes — test as many patterns as you like for free, with no account or usage limit.