How to Test Regular Expressions, Named Groups, and Glob Rules Safely
Untested regular expressions cause subtle validation bugs and catastrophic backtracking in production. Testing against realistic multi-line fixtures locally keeps log lines and customer strings private.
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Regex Tester, Highlighter & Pattern Studio
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Step-by-Step Guide
- 1
Enter pattern and ECMAScript flags
Toggle `g`, `i`, `m`, `s`, `u`, and `v` flags and inspect syntax errors immediately.
- 2
Paste multi-line test fixtures
Review every match index, numbered group, and `(?<name>...)` capture in a structured table.
- 3
Preview string replacements or glob matches
Test `$1` / `$<name>` substitutions or switch to `.gitignore` `!negation` matcher.
Who This Is For
Backend, SRE & Frontend Developers
Validating log parsers, input validators, URL routers, and `.gitignore` patterns.
Frequently Asked Questions
Does my test text stay inside my browser?
Yes. Pattern execution runs natively in your browser's JavaScript engine with zero network calls.