Regular Expression (Regex) Tester
Local ProcessingTest regular expressions in real-time against sample text with flag support and match highlighting.
How It Works & Processing Standards
Test regular expressions in real-time against sample text with flag support and match highlighting.
Tool processing runs in your browser. If you create a calculator or conversion share link, its values are included in the URL. See the privacy policy for account, analytics and advertising data.
Current Limits
- Maximum input length: 100,000 characters
Check a regex does what you intend before putting it in code. It runs on the browser’s JavaScript regex engine, so results match your JS code.
What You Can Do
- Matches and position
- How many matches, the first one and its character index.
- Group count
- How many capture groups ( ) the pattern has.
How to Use Regular Expression (Regex) Tester
- 1Enter pattern and flagsType the pattern without slashes, plus flags.
- 2Enter textPaste the text to test.
- 3Read the resultSee the match details.
Examples
Find numbers
Input: \d+, g / a1 b22 c333
Result: 3 matches, first 1 (index 1), 0 groups
Email with two groups
Input: (\w+)@(\w+)\.com, g / me@site.com, you@web.com
Result: 2 matches, first me@site.com, 2 groups
Common Use Cases
- Building validation regexes
- Checking patterns to pull from logs
Frequently Asked Questions (FAQ)
Is it the same as Python or Java regex?
Mostly, but details such as lookbehind or named-group syntax can differ. This tool follows JavaScript rules.