Regex Visualizer
Visualize a regex pattern as a railroad/syntax-tree diagram with color-coded components.
What is Regex Visualizer?
A regex visualization tool that draws a railroad diagram from a regex pattern. Each construct is rendered as a labeled box: literal characters, character classes, groups, quantifier loops, alternation branches, and anchors.
How it works
We parse the regex into an AST (abstract syntax tree), then render each node as an SVG box connected by arrows, using color coding by token type.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Seeing the structure
Visualize a pattern as a graph — watch how alternation branches and quantifiers loop before you trust the pattern.
Common mistakes
The graph isn't the engine
The visualization reflects the pattern's structure — flags and backtracking behavior still depend on the engine.
Frequently asked questions
What's a railroad diagram?
A railroad (or syntax) diagram is a flowchart that shows the path through a pattern. Boxes represent tokens, loops show repetition, and branches show alternation — much easier to read than the raw regex.