Regex Tester

Test regular expressions with live match highlighting

Regular expressions are compact but unforgiving, and one stray quantifier can make your pattern match everything or nothing. This regex tester lets you write a pattern, apply flags, and instantly see every match highlighted inside your sample text, so you can refine the expression until it captures exactly what you intend.

How it works

The tool uses your browser's native JavaScript regular-expression engine, so behaviour matches what you get in Node.js and front-end code. Type a pattern and toggle flags like g, i, m, and s; matches and capture groups update as you type. Everything runs locally, so you can test patterns against sensitive log samples without anything leaving your device.

Practical use cases

• Validate email, URL, or phone formats before shipping a form.
• Extract capture groups from log lines or scraped text.
• Prototype a search-and-replace pattern, then apply it in Find and Replace.
• Check which characters need escaping with the Backslash Escape / Unescape tool.

Comparing two versions of a pattern's output? The Text Diff Checker makes the differences easy to spot.

Private and free

Because matching happens entirely client-side, your patterns and test text stay in your browser, with no upload, no account, and no tracking. The regex tester is free and works on every modern browser, including mobile.