Regex Tester

The Regex Tester lets you test regular expressions in real time, with visual match highlighting in the text as you type. Building a correct regex on the first try is rare — it almost always requires iteration, adjusting the pattern, and verifying that it captures what it should without capturing what it should not. This tool significantly speeds up that process.

To use it, write your regular expression in the pattern field and the text you want to test against in the text field. Matches are highlighted instantly, with no button to press. You can enable the most common flags — global (g), case-insensitive (i), multiline (m) — with checkboxes, and see detailed capture groups for each match found.

The tool is particularly useful for validating formats like emails, phone numbers, postal codes, and URLs; for extracting information from log strings; for building input sanitization rules; and for learning regular expressions by exploring how different patterns behave in practice.

Frequent use cases: writing form validators, building text file parsers, creating find-and-replace rules in code editors, and debugging existing regexes that are not behaving as expected. All processing happens in your browser's native JavaScript engine, with no data sent externally.