Regex Tester
Free · No Sign-up · No AdsTest regular expressions with live match highlighting, capture group visualization, and replace mode. Runs entirely in your browser.
Pattern uses: one or more
Hello World! The quick brown fox jumps over the lazy dog.
Contact us at hello@example.com or support@deepchill.appWhat is a Regex Tester?
A regex tester lets you write a regular expression pattern and immediately see which parts of a test string it matches, highlighted in real time. It also shows individual match positions, capture group contents, and a replace preview — all without any page reload.
Why use Deepchill's Regex Tester?
Deepchill's Regex Tester uses the native JavaScript RegExp engine in your browser for zero-latency matching. It includes catastrophic backtracking protection via debouncing and try/catch, a curated preset library for common patterns, color-coded capture groups (up to 6 levels), and a replace mode with $1/$2 backreference support.
Common Use Cases
- Form validation: Build and test email, phone, or postal code patterns before wiring them into your frontend validation logic.
- Log parsing: Extract timestamps, request IDs, or error codes from log lines using capture groups, then copy the pattern for use in grep or your logging tool.
- Text transformation: Use replace mode to preview bulk text changes — for example reformatting dates from YYYY-MM-DD to MM/DD/YYYY using capture groups.
- Teaching regex: Use the live highlights and match list to demonstrate what each quantifier and character class matches as you type.
Example
Pattern + test text → Matches with capture groups
Input
/([a-z]+)@([a-z]+)\.([a-z]{2,})/gi
Test: hello@example.comOutput
Match 1: hello@example.com
$1: hello $2: example $3: com