Free Regex Tester & Debugger Online — Quickly test and debug Regular Expression...
Quickly test and debug Regular Expression capture groups against real-time text arrays.
Example: Extracting emails with `([a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9_-]+)` and flags `gi`.
Test String Data
Evaluated Match Results 0 matches
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How to Use the Regex Tester Online
Mastering regular expressions is notoriously difficult, but our free regex tester online makes it visual and intuitive. To get started, type your regular expression into the "Regular Expression" input field at the top. You can append standard regex flags (like g for global, i for case-insensitive, or m for multiline) in the adjacent box.
Next, paste the text block you want to analyze into the "Test String Data" area. As a real-time regular expression debugger, the tool will instantly highlight matching text strings and independently isolate your regex capture groups in the right-hand results panel. There is no need to press enter or refresh the page.
Why Developers Need a Regex Match Tool
Form Validation
Before writing backend code, developers test regex pattern online to ensure their custom email, password strength, and phone number validation logic is bulletproof and doesn't accidentally block legitimate users.
Web Scraping
Data analysts and Python developers frequently use regex to scrape data from messy HTML files. This tool helps them isolate the exact HTML tags or JSON strings they need to extract.
Log Parsing
DevOps engineers use regular expressions to sift through massive server error logs, allowing them to quickly isolate 500 errors, specific IP addresses, or database timeouts.
Find and Replace
Content managers rely on regex to perform complex find-and-replace operations across thousands of lines of text (e.g., swapping date formats from MM/DD/YYYY to YYYY-MM-DD).
Quick Regex Cheat Sheet
| Token | Description |
|---|---|
| \d | Matches any digit (0-9). Equivalent to [0-9]. |
| \w | Matches any word character (alphanumeric & underscore). |
| \s | Matches any whitespace character (spaces, tabs, line breaks). |
| ^ and $ | Matches the start (^) and the end ($) of the string. |
| (...) | Capture Group. Extracts the matched text for back-referencing. |
Frequently Asked Questions
What regular expression engine does this use?
This tool acts as a javascript regex tester because it runs purely in your browser using the V8 JavaScript RegExp engine (or your browser's equivalent). This means the syntax and rules exactly match what you would expect when writing Node.js or front-end JS applications.
Why isn't my pattern matching multiple lines?
Ensure you have added the g (global) flag in the flags box. Without the global flag, the regex engine will stop searching immediately after it finds the very first match.
Are my texts and regex patterns saved?
No. All testing is performed entirely client-side. We do not store, log, or track the text data you paste into the tester, making it perfectly safe for debugging proprietary logs or API responses.