Enter a JavaScript regex pattern and flags such as g, i, or m.
Developer tool
Regular Expression Tester
Enter a JavaScript regular expression and flags to inspect matching ranges, capture groups, and replacement output against test text.
Test a JavaScript regular expressionInspect matches, groups, and replacement output.
LOCALReplaced text
Today is 2026/08/28.#1 2026-08-28 → [2026, 08, 28] @ 9
Complete guide
How to use Regular Expression Tester
When to use it
Enter a JavaScript regular expression and flags to inspect matching ranges, capture groups, and replacement output against test text.
01
Three-step workflow
- 1
Enter a JavaScript regex pattern and flags such as g, i, or m.
- 2
Paste test text and inspect match positions and capture groups.
- 3
Add a replacement expression to preview transformed output.
02
What to enter and check
Invalid patterns or duplicate flags show an error, and match display is capped at 100.
The tester follows browser JavaScript RegExp syntax, which can differ from other languages.
Practical example
Match 2026-08-28 with (\d{4})-(\d{2})-(\d{2}) and replace it using $1/$2/$3.
How to read the result
The tester follows browser JavaScript RegExp syntax, which can differ from other languages.
05
Before you use the result
- Regular-expression syntax can differ between JavaScript and other languages.
- Escape user input and review ReDoS risks before using dynamic patterns.
06
Frequently asked questions
How should I read the Regular Expression Tester result?+
The tester follows browser JavaScript RegExp syntax, which can differ from other languages.
What should I check for a more accurate Regular Expression Tester result?+
Invalid patterns or duplicate flags show an error, and match display is capped at 100. Regular-expression syntax can differ between JavaScript and other languages.
Is my input uploaded or stored?+
No. This tool processes input in your current browser, and Baro Tool does not store the source content or result on its server.