Regex Tester
A regex tester helps you iterate on a regular expression before putting it into application code. This tool uses JavaScript regular-expression behavior.
Quick answer
Test JavaScript regular expressions against sample text and inspect matches. The core operation is designed for quick browser-based use without an account.
How to use this tool
- Enter a pattern and test text
- Choose the needed flags
- And inspect the matches or errors.
Common errors and things to check
Remember that JavaScript regex syntax differs from some other regex engines. Escape characters and zero-length patterns can also affect results.
Common use cases
- Debugging validation patterns
- Testing search expressions
- Learning regex behavior
Privacy and local processing
Core processing for this tool is designed to happen in your browser. The page does not intentionally upload ordinary tool input to a DataToolBase server. Do not paste passwords, private keys, access tokens, personal data, or other sensitive secrets unless you have verified the security requirements for your use case.
Frequently asked questions
Which regex engine is used?
The browser JavaScript regular-expression engine is used.
Why does my regex behave differently elsewhere?
Regex dialects differ. A pattern written for PCRE, Python, .NET, or another engine may need changes for JavaScript.