Regex Tester
Test regular expressions against sample text with live match highlighting.
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What is Regex Tester?
A regex tester lets you validate patterns against sample strings before using them in code or search-and-replace.
How to use
Enter your regex pattern and flags.
Paste test text.
Review matches and groups.
Benefits
- Live match feedback
- Supports common flags
- Debug patterns quickly
Frequently Asked Questions
Which regex flags are supported?
Enter standard JavaScript flags like g, i, m, s, and u in the flags field. The global flag is added automatically when listing all matches.
Why do I see no matches?
Check for typos, missing anchors, or flags. Case-sensitive patterns won't match different casing unless you add the i flag.
Can I test capture groups?
Yes. Matches are listed, and grouped captures are collected internally — use parentheses in your pattern to extract substrings.
Is this tool free?
Yes. This tool is completely free to use with no sign-up, no limits, and no hidden fees.
Does my data leave my browser?
No. All processing happens entirely in your browser using client-side JavaScript. Your data is never sent to a server or stored anywhere.
Does this tool work on mobile?
Yes. PeasyDo tools work in modern mobile browsers on iOS and Android. For file tools, use a browser that supports file uploads and downloads.
Do I need to install software?
No. Everything runs in your browser — no desktop app, plugin, or account required.
Feedback & report a problem
Found a bug or have a suggestion? Let us know — it helps us improve this tool.
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