Regex Tester

Test and debug regular expressions with real-time matching and highlighting.

Regular Expression

Test String

Common Patterns

About Regex Tester

Free online regex tester that lets you write and test regular expressions with real-time pattern matching and match highlighting. See captured groups, test against multiple strings, and choose from a library of common regex patterns for emails, URLs, phone numbers, and more. Supports JavaScript regex syntax with flags for global, case-insensitive, and multiline matching.

Frequently Asked Questions

What regex syntax does this tool support?▾

The tool uses JavaScript regular expression syntax, which covers the vast majority of common regex patterns. It supports flags like global (g), case-insensitive (i), and multiline (m).

Can I see captured groups in my regex matches?▾

Yes. The tool displays all captured groups for each match, making it easy to debug complex patterns with parenthesized sub-expressions and named capture groups.

Does it include common regex patterns?▾

Yes, the tool includes a library of pre-built patterns for validating emails, URLs, phone numbers, IP addresses, dates, and more. You can load any pattern with one click and customize it to your needs.

What are regex flags and when should I use them?▾

Regex flags modify how the pattern is applied. The 'g' (global) flag finds all matches instead of stopping at the first. The 'i' flag makes the search case-insensitive. The 'm' (multiline) flag makes ^ and $ match the start/end of each line rather than the entire string. Use combinations to match your specific needs.

How do I learn regular expressions?▾

Start with simple patterns like literal text matching, then learn character classes (\d for digits, \w for word characters), quantifiers (+, *, ?), and grouping with parentheses. This tool's real-time highlighting and built-in pattern library make it an excellent learning environment - try modifying the pre-built patterns to see how each component works.

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