Regex Tester
The Regex Tester helps you test regular expressions against sample text and understand which parts of your input match a pattern. Debug expressions, check matching behavior, and refine patterns for validation, text extraction, and search operations. This free online regular expression tester is useful for developers, data analysts, and anyone working with text patterns. Enter your regex and test string to inspect the results and fine-tune your expression.
Test an email-like string with a regular expression. Load the example to see the tool in action.
Matches update automatically. Common flags: g (global), i (ignore case), m (multiline), s (dotAll), u (Unicode).
What is Regex Tester?
A Free Regex Tester lets you test regular expressions against sample text and inspect which parts of the input match your pattern. Use this free online regular expression tester to learn regex syntax, troubleshoot pattern matching, and refine rules for text validation, searching, and data extraction.
Why use this tool?
- Test a pattern against realistic sample input before putting it into code.
- Experiment with anchors, character classes, groups and quantifiers.
- Reduce trial-and-error when debugging a regular expression.
How to use Regex Tester
- Step 1. Enter the regular expression pattern.
- Step 2. Provide representative test text.
- Step 3. Review matches and refine the expression for the exact requirement.
Common use cases
Test a regular expression in JavaScript
Use a small test case to check whether a pattern matches the text you expect.
const pattern = /^[A-Z]{2}\d{4}$/;
const value = "AB1234";
console.log(pattern.test(value)); // trueTools to use next
Continue the task with related utilities for the next step in your workflow.
Important notes
- A regex that matches one sample does not necessarily implement a complete validation rule.
- Prefer readable patterns and test edge cases before using them in production.
More Code & Formatting Tools
Regex Tester FAQ
What is a regular expression?
A regular expression is a pattern language used to find, match or transform text.
Why does my regex match too much?
Broad character classes, greedy quantifiers and missing anchors are common causes. Test smaller cases and add explicit boundaries.