Free Online Regex Tester
The regex tester runs a JavaScript regular expression against sample text in real time, highlighting every match and exposing capture group values.
Your data is processed entirely in your browser and never sent to any server.
How to Use This Developer Tool
- Type your pattern into the pattern field.
- Toggle flags (g, i, m, s, u, y) as needed.
- Paste sample text into the input.
- Read inline match highlights and the capture group table below.
What Is a Regex Tester?
Regular expressions are precise but unforgiving — a missing escape, the wrong quantifier, or a forgotten flag can quietly mismatch and ruin an afternoon of debugging. A live tester surfaces exactly what your pattern matches as you type, which is the fastest way to build intuition for a stubborn pattern.
This tester uses the browser's native ECMAScript regex engine. It highlights matches inline, lists each capture group's value, and toggles every flag (`g` for all matches, `i` for case-insensitive, `m` for multiline `^`/`$`, `s` for dotall, `u` for Unicode, `y` for sticky). Useful for debugging a log-parsing pattern, prototyping a URL router, or validating a form input rule before shipping it.
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.
Related Developer Tools
Format and beautify JSON data with proper indentation and syntax highlighting. Validates JSON structure while formatting.
Encode text for use in URLs. Convert special characters to percent-encoded format.
Convert Markdown to HTML. Transform markdown documents into styled HTML for web pages.