Free Regex Tester Online
Test regular expressions instantly with live feedback, match highlighting, and replacement support. This free regex tester is useful for developers, data analysts, and anyone working with patterns or validation rules.
Result:
Common Patterns:
- Email: ^\w+@\w+\.\w+$
- URL: https?://[^\s]+
- Phone: ^\d{3}-?\d{3}-?\d{4}$
- IP Address: \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}
How to Use:
- Type or paste your regex pattern into the pattern field.
- Paste the text you want to test the pattern against.
- Toggle Global, Ignore Case, or Multiline flags as needed.
- Click Test Regex to see matches highlighted, or Replace Matches to substitute them.
What is a Regex Tester?
A regular expression (regex) is a sequence of characters that defines a search pattern, used for validating input, extracting data, or finding and replacing text based on a rule rather than an exact match. Writing regex correctly by hand is error-prone — a single misplaced character can silently break a pattern. A regex tester lets you type a pattern and immediately see which parts of your sample text it matches, so you can debug and refine it before using it in real code, a form validator, or a data-cleaning script.
Who uses this tool
- Developers validating form input like emails, phone numbers, or usernames
- Data analysts extracting or cleaning structured data from unstructured text
- QA engineers writing test patterns for input validation logic
- Students learning regex syntax with instant visual feedback
Frequently Asked Questions
What does the Global (g) flag do?
Without the global flag, a regex stops after finding the first match. With it enabled, the tester finds and highlights every match in the text, not just the first one.
Why isn't my pattern matching anything?
Common causes include a missing flag (like Ignore Case for mixed-case text), an unescaped special character (like a literal "." that should be "\."), or a pattern anchored with ^ and $ that doesn't match the full line. Try simplifying the pattern to isolate the issue.
Is this tool free and does it store my data?
Yes, it's free to use. Pattern testing runs in your browser, so your input text isn't required to be sent to a server for the core matching function.