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JSON Validator
The other half of validating config and exported data.
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Regex Tester
Watch matches highlight live as you type a pattern — with capture groups, flags, and honest error messages when a pattern doesn't compile.
Test a regular expression
Matches
Waiting for a pattern…
Match details
| # | Index | Full match | Groups |
|---|
How it works
How the regex tester works
Real JavaScript
Patterns are compiled with the platform's own RegExp engine, so a valid pattern here runs identically in your code. Invalid patterns produce the same errors you would see in the console.
Highlighted context
The sample text is redrawn with each match marked in place — the first in purple and the rest in green — so you can see exactly what the pattern covers and what it leaves alone.
Groups made visible
Capturing groups appear in the details table, position by position. Great for debugging template substitutions like $1/replace logic.
Questions
Regex tester FAQ
Which regex flavor does this use?
JavaScript/ECMAScript — the same engine browsers and Node use, so a pattern validated here behaves identically in your code.
Why is my pattern matching nothing?
Check flags first: without g only the first match is reported. Then check specials — . [ ] ( ) * + ? { } | \\ are all meaningful, so escape any literal one with a backslash.
What do the highlight colors mean?
Purple marks the very first match of the run; green marks every subsequent one. The rest of the text did not match.