Developer
Regex tester
Test JavaScript regular expressions with live matches, groups, and replacements.
Free to use · Runs in your browser · No signup
This tool works in your browser. Enable JavaScript to select files and create your download.
How to use Regex tester
- Enter a regular expression and its flags.
- Paste test text and review each match, its position, and capture groups.
- Optionally enter a replacement to preview the result.
What you need
Nothing to upload. Type or paste directly into the tool; results update as you go.
Your result
Matches, capture groups, and an optional replacement preview.
Before you start
Uses the JavaScript regex engine in your browser. Patterns that take too long are stopped automatically to protect the page.
Questions about Regex tester
How do I use Regex tester?
Enter a regular expression and its flags. Paste test text and review each match, its position, and capture groups. Optionally enter a replacement to preview the result.
What does Regex tester produce?
Matches, capture groups, and an optional replacement preview.
What should I check before using Regex tester?
Uses the JavaScript regex engine in your browser. Patterns that take too long are stopped automatically to protect the page.
Is what I type sent anywhere?
No. The calculation runs in your browser, and the text or numbers you enter are not uploaded or stored.