Developer Utilities
Regex Tester
Regular expressions are powerful but notoriously easy to get subtly wrong — a pattern that matches your first test case might fail on an edge case you didn't think of. This free regex tester lets you try a pattern against sample text and see every match highlighted live as you type, along with a running match count and any captured groups, so you can iterate quickly instead of testing blindly in your actual code. It uses standard JavaScript regular expression syntax — the same engine that powers browsers and Node.js — making it a natural fit for testing patterns you'll use in JavaScript or TypeScript.
Processed entirely in your browser — your files are never uploaded anywhere.
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How to use this tool
- Type a pattern (without the surrounding slashes).
- Toggle flags like global or ignore case as needed.
- Paste text to test against — matches highlight automatically.
Frequently asked questions
- What regex flavor does this use?
- Standard JavaScript regular expression syntax (the same engine used by browsers and Node.js) — slightly different in places from PCRE or Python's re module.
- Why do I only see one match?
- Enable the Global (g) flag to find every match in the text instead of stopping at the first one.
- Can I test regex for languages other than JavaScript?
- This tool uses JavaScript's regex engine specifically, which is similar to but not identical to PCRE (PHP) or Python's re module — most common patterns behave the same, but some advanced features differ.
- How do I capture and view groups in my match?
- Add parentheses around the part of your pattern you want to capture, e.g. (\d+) — matched groups appear listed below each match in the results.
- Is my test text uploaded anywhere?
- No — all matching happens locally in your browser using JavaScript's built-in RegExp engine. Nothing you type is sent to a server.