Regex Tester
Test a regular expression against target text and inspect highlights, indices, and capture groups.
JSON FormatJSON ValidateBase64URL EncodeTimestampUUIDJWT DecodeHashRegexHTML EntitySQL FormatYAML to JSONJSON to YAML
Settings
Flags
Input
Type or paste content directly. Processing stays in the browser whenever possible.
Example data
Output
Process some input and the result will appear here.
Process some input and the result will appear here.
How to use
Enter the regex pattern and flags in settings.
Paste the text to test in the input area.
The output shows highlighted matches, match count, and capture groups.
Best for
Debug patterns for email, phone numbers, or logs.
Validate frontend form rules quickly.
Check how g, i, and m flags affect matches.
FAQ
Which flags are supported?
The first version supports g, i, and m.
Will all matches be highlighted?
With g enabled, all matches are highlighted. Without it, only the first match is shown.
What happens with invalid regex syntax?
The page shows the RegExp construction error immediately.