What is Regex Visualizer?
A regex visualizer is an interactive tool that breaks down a regular expression into its component tokens and explains what each part matches. It also lets you test the regex against sample text, highlighting matches in real time and showing captured groups. This makes it much easier to understand, debug, and write regular expressions.
How to Use
- Enter your regex pattern in the pattern input field. Use the surrounding slashes as a visual guide.
- Set the desired flags (g for global, i for case-insensitive, etc.) using the checkboxes or the flags input.
- Type or paste a test string in the text area to test your pattern against.
- Click the Test button to run the regex. Matches will be highlighted in the test string, and the pattern breakdown will explain each token.
Why Use This Tool?
Tips & Best Practices
- Use the 'g' flag to find all matches in the test string, not just the first one
- Named capturing groups (?<name>...) make group captures easier to read than numbered groups
- Start with a common pattern from the dropdown, then modify it to fit your needs
Frequently Asked Questions
What is a regex visualizer?
A regex visualizer is a tool that parses a regular expression and explains each token (character classes, quantifiers, groups, anchors, etc.) in plain language. It also lets you test the regex against text and see matches highlighted.
What regex syntax does this tool support?
This tool supports JavaScript (ECMAScript) regular expression syntax, including character classes, quantifiers, groups (capturing, non-capturing, named, lookahead), anchors, escape sequences, and unicode mode.
How do I fix an invalid regex error?
The tool displays a clear error message when your pattern is invalid. Common issues include unmatched brackets, invalid escape sequences, or incorrect quantifier placement. Read the error message carefully and adjust your pattern accordingly.
What is the difference between capturing and non-capturing groups?
Capturing groups (parentheses) save the matched content for later reference, accessible via match[1], match[2], etc. Non-capturing groups (?:...) group the pattern logically without saving the match, which is slightly faster and avoids polluting the match result.
Can I use this to learn regex?
Absolutely! The pattern breakdown explains each token in plain language. Start with a common pattern from the dropdown, observe how it works, then modify it step by step. The visual feedback from match highlighting makes it easy to see the effect of each change.