Regex Validator

This tool validates your regular expression using the browser's native RegExp constructor, which follows the ECMAScript specification. It then analyzes the pattern's structure to provide a breakdown of its components and detect potential issues. All processing happens in your browser — no data is sent to any server.

What Gets Checked

• Syntactic validity — unmatched brackets, parentheses, or braces
• Quantifier placement — quantifiers applied to valid targets
• Escape sequences — properly escaped special characters
• Character class syntax — valid ranges and negation
• Group syntax — capturing, non-capturing, and lookahead/lookbehind
• Flag compatibility — valid flag combinations

Pattern Analysis

Beyond syntax checking, the tool provides a structural breakdown of your pattern showing each component's meaning, plus warnings about common issues:

• Nested quantifiers — patterns like (a+)+ that can cause catastrophic backtracking
• Unescaped metacharacters — characters that may need escaping for literal matching
• Overly broad patterns — .* without anchors that may match more than intended
• Empty alternatives — patterns like a| with empty branches

Common Regex Tokens

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.