正規表現解説 - Free Online Tool | PivaBox

Understand any regular expression — breaks down patterns into plain English explanations token by token

How to Understand Regular Expressions

1. Type or paste a regular expression in the pattern input — the tool will automatically parse and explain every token
2. Read the plain-English breakdown to understand what each part of the regex does — metacharacters, quantifiers, groups, and character classes
3. Optionally paste test text to see real-time match results and verify your understanding

Frequently Asked Questions

Is Regex Explainer free?

Yes, it is completely free. All parsing runs locally in your browser using JavaScript.

What regex features are supported?

The explainer covers character classes, quantifiers, anchors, capturing and non-capturing groups, lookaheads, alternation, and all common escape sequences.

Does it support regex flags?

Yes, you can add flags (g, i, m, s, u) which affect how matches are found in the test text area.