Regex Tester & Replace
Free online regex tester with built-in cheat sheet for mobile numbers, emails, IPs, ID numbers and more, plus match highlighting and replace preview.
Tool Guide
About the Online Regex Tester
Test regular expression matches in real time, with a built-in cheat sheet of common patterns — mobile numbers, emails, IPv4 addresses, ID numbers, Chinese characters, date formats, and pure integers — ready to apply with one click.
Key Features
1. Common Pattern Cheat Sheet
Seven frequently-used regex templates built in, so you can test common formats without writing them by hand.
2. Real-Time Match Highlighting
Enter text and a pattern, and every match (with its capture groups) is highlighted automatically.
3. Replace Preview
Enter a replacement string and preview the result of the substitution live.
How to Use
Step 1: Enter the text to test, or click a cheat-sheet entry to fill in a common pattern.
Step 2: Enter or adjust the regex pattern and flags (e.g. g, i).
Step 3: Review the matches, and optionally enter a replacement string to preview the result.
Use Cases
Useful for debugging form-validation rules, extracting text from logs, data cleaning, and testing regex shared between front-end and back-end code.
FAQ
Which regex flags are supported?
Standard JavaScript regex flags, such as g (global) and i (case-insensitive).
What happens if the pattern is invalid?
The tool shows a syntax error — check that parentheses and escape characters are correct.
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