Regex Tester

Test regular expressions live against sample text.

Pattern

//g

Global (g)Ignore case (i)Multiline (m)Dot-all (s)

Quick patterns:

Test string

Related Tools

Formatter

JSON Formatter & Validator

Format, validate, and minify JSON. Real-time error detection with line numbers.

Security

JWT Decoder

Decode JSON Web Tokens instantly. Inspect header, payload, and expiry — fully client-side, no signature verification.

// more about this tool

Live matching against real sample text

Write a pattern and test text side by side, and matches highlight as you type, along with capture groups broken out individually. This matters because regex is notoriously easy to get subtly wrong, a pattern that matches your one example input can fail on the next one, and the only reliable way to catch that is testing against real, varied sample strings, not just staring at the pattern.

Flags and what they change

Toggle the common flags, global (match all occurrences instead of stopping at the first), case-insensitive, and multiline (so ^ and $ match the start/end of each line instead of the whole string), and see the match set update immediately. Dart's RegExp class supports the same core syntax as JavaScript's, so a pattern validated here generally carries straight over into Dart code.