Text & Regex Tools
Regex Tester
Test JavaScript regular expressions against sample text, or replace matches locally with flags, highlighting, and capture groups. Processing happens in your browser.
Enter a pattern and test string, then click Test Regex.
Highlighted preview
Matches will be highlighted here after you test.
Replacement result
Read-onlyMatch results
Match details will appear here after you test.
About this tool
Regex Tester runs JavaScript regular expressions locally so you can
test matches or replace text with $1 and other native
replacement tokens.
- Runs entirely in your browser
- Test and Replace modes share pattern, flags, and test string
- Supports flags: g, i, m, s, and u
- Input is limited to 1 MB per field; Test shows up to 500 matches
- Complex patterns on large text may slow your browser — test carefully