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Regex Tester
Test JavaScript regular expressions against sample text
Runs locally in your browser
Regex
Text
Matches
- Hello
- world
- test
How it works
Tests JavaScript regular expressions against sample text and lists all matches with your chosen flags—ideal for quick pattern iteration before committing to code.
Who it's for: Developers, data analysts, and technical SEOs validating extract-and-replace patterns
Runs patterns using the JavaScript RegExp engine—the same behavior as in Node and browsers.
Supports global, ignore-case, multiline, and other standard flags.
Surfaces syntax errors immediately when a pattern is invalid.
How to use
- Enter the pattern without surrounding slashes (e.g., [a-z]+ or \d{3}-\d{4}).
- Set flags such as g, i, m, or gi in the flags field.
- Paste sample text in the test string area.
- Review the match list for each full match and capture groups if present.
- Refine the pattern until matches align with your intent, then copy into your codebase.
Good to know
- Lookahead and lookbehind require modern JavaScript engines; very old browsers may differ.
- Catastrophic backtracking on huge inputs can freeze the tab—test with a representative sample first.