About this tool
Regex Tester is a free online tool that tests regular expressions against your text in real time. See matches highlighted, inspect capture groups, toggle flags, and copy the full pattern. Everything runs locally in your browser using the native JavaScript RegExp engine.
How it works
1
Enter a regular expression
Type or paste a regex pattern. Or pick a preset from the list (email, URL, phone, date, IP). The pattern validates as you type.
2
Add test text
Paste or type the text you want to test. Matches are highlighted live. Toggle flags (g, i, m, s, u, y) to change matching behavior.
3
Inspect matches
See every match with its position and numbered or named capture groups in a table below. Copy the full /pattern/flags to your clipboard.
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Frequently Asked Questions
What regex engine is used? v
The tool uses the native JavaScript RegExp engine built into your browser. This is the same engine used by JavaScript, TypeScript, and Node.js. It is not PCRE, Python, Go, or .NET.
What flags are supported? v
All six standard JavaScript flags: g (global), i (case-insensitive), m (multiline), s (dotall), u (unicode), and y (sticky). Toggle them in the flags section.
Are my patterns and text sent to a server? v
No. Everything is processed locally in your browser. No patterns, text, or matches leave your device.
Can I test patterns for other languages? v
The tool runs JavaScript RegExp only. Patterns for PCRE, Python, Go, or .NET may behave differently. Use the appropriate engine's playground for those.