Free Online Regex Tester
A regex tester lets you write a regular expression and a sample string side by side, then highlights every match, every capture group, and every flag-controlled behaviour as you type.
Your data is processed entirely in your browser and never sent to any server.
How to Use This Developer Tool
- Type your regular expression into the pattern field.
- Toggle flags (`g`, `i`, `m`, `s`, `u`, `y`) as needed.
- Paste your sample string into the input.
- Every match is highlighted in the input and listed below with capture-group values.
What Is a Regex Tester?
Regular expressions are powerful but unforgiving — a missing escape, a greedy vs. lazy quantifier, or the wrong flag is enough to ruin an evening of debugging. A live tester surfaces exactly what your pattern matches in real time and what it doesn't.
This tester runs your pattern against your sample using the JavaScript regex engine and shows every match in context, every capture group's value, and the impact of each flag (`g`, `i`, `m`, `s`, `u`, `y`). It also exposes the `test()` and `exec()` distinction for engineers porting patterns between languages.
Frequently Asked Questions
What regex flavor is supported?
Can I test with multiple strings?
How do I debug a regex?
References
Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.
Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.
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