Regex Tester & Debugger
Test, debug, and execute Regular Expressions in real-time right in your browser. Supports global, multiline, and insensitive flags with match grouping.
Regular Expression
Test StringEdit text below
Match Results0 Matches
No matches found in the test string.
Real-time Client-Side Regex Testing
Our RegEx (Regular Expression) Tester evaluates your patterns instantly as you type. Everything happens exclusively within your browser utilizing the JavaScript Regex Engine (V8). We don't send your regex patterns or test strings to any external servers, ensuring you can safely test matching against sensitive logs or PII (Personally Identifiable Information).
Common Regular Expression Flags
- g (Global): By default, a regex will stop after the very first match it finds. The Global flag tells the engine to continue searching for all possible matches throughout the entire document.
- i (Insensitive): Case-insensitive matching. This makes
amatch bothaandA. - m (Multiline): Changes the behavior of
^(start of line) and$(end of line) anchors. Instead of matching the start and end of the entire string, they will match the start and end of each individual line (separated by \n). - s (Dotall): Allows the dot character (
.) to match newline characters. By default, a dot matches any character except line breaks.
Helpful Regex Cheat Sheet
| Characters & Anchors | Description |
|---|---|
| . | Any single character (except newline) |
| \w \d \s | Word, digit, whitespace |
| \W \D \S | Not word, digit, whitespace |
| [abc] | Any of a, b, or c |
| [^abc] | Not a, b, or c |
| ^ $ | Start / End of string (or line) |
The tools and calculators provided on The Simple Toolbox are intended for educational and informational purposes only. They do not constitute financial, legal, tax, or professional advice. While we strive to keep calculations accurate, numbers are based on user inputs and standard assumptions that may not apply to your specific situation. Always consult with a certified professional (such as a CPA, financial advisor, or attorney) before making significant financial or business decisions.
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