Regular Expression Tester
Write, test, and debug Javascript RegExp patterns completely localized securely against private custom text strings.
How to Use the Free Regex Tester
Our Regular Expression (Regex) Tester provides an intuitive interface to build and debug complex pattern matching operations. Enter your custom Regex pattern and flags (like `g` or `i`) at the top. Paste your testing corpus into the left pane, and instantly see dynamic highlights of matching characters appearing on the right, accompanied by an exact array extraction.
Key Features
- Live Highlights: Visualize exactly where and how your execution pattern matches text characters instantly.
- Javascript RegExp Engine: Fully supports native ES6 regex standards including lookaheads, lookbehinds, and named capture groups.
- Array Extraction: See exact matches separated in a scrollable list to debug unintended partial matches.
- Data Security: The parser acts entirely offline natively, ensuring proprietary log files or user data strings are protected safely from exposure.
Frequently Asked Questions
What are Regex flags?
Flags modify how the pattern seeks matches. The most common are `g` (global search, don't stop after the first match), `i` (case-insensitive search), and `m` (multiline matching for start/end anchors).
Are patterns different than Python Regex?
Our tool natively utilizes the JavaScript internal RegExp engine which adheres to ECMA standards structure. While it's visually 95% similar to Python and PCRE logic, microscopic differences in named group syntax or lookbehinds may occur.