Mermaid Viewer
Preview Mermaid Diagrams with Themes & Layout Presets
Mermaid Viewer is an online tool that helps you preview and render Mermaid diagrams in real time. Paste your Mermaid code and instantly see how it looks with different themes, layout presets, and styles. Whether you are creating flowcharts, system architecture diagrams, or documentation visuals, Mermaid Viewer makes it easy to explore how your diagrams appear in presentations, documents, and technical designs.
Mermaid Preview in Real Time
Mermaid Viewer provides a live Mermaid preview experience. As you edit your Mermaid diagram code, the rendered diagram updates instantly, allowing you to focus on structure and clarity without switching tools. This makes Mermaid Viewer ideal for developers, product managers, and technical writers who need fast and accurate Mermaid diagram previews.
Explore Mermaid Themes and Styles
Mermaid Viewer supports multiple Mermaid themes, including hand-drawn styles inspired by Excalidraw, dark mode themes, neutral themes for print, and customizable base themes. Compare different Mermaid diagram themes to find the best visual style for your documentation, presentations, or architecture diagrams.
Mermaid Layout Presets for Different Use Cases
Different diagrams require different spacing and visual density. Mermaid Viewer offers layout presets such as Presentation, Standard, Compact, and Architecture layouts. These Mermaid layout presets help you control spacing, line style, and overall readability, making your diagrams suitable for slides, technical documentation, or system design reviews.
Built for Documentation, Architecture, and Presentations
Mermaid Viewer is designed for common real-world use cases:
- Preview Mermaid diagrams for technical documentation
- Style Mermaid diagrams for system architecture designs
- Prepare Mermaid diagrams for presentations and slides
- Experiment with Mermaid themes before exporting diagrams
If you already write Mermaid code, Mermaid Viewer helps you see the final result clearly and efficiently.
Why Use Mermaid Viewer?
Mermaid Viewer focuses on preview, styling, and layout — not diagram generation. If you already use Mermaid syntax, this tool gives you better control over how your diagrams look, without locking you into complex editors or proprietary formats. It works directly in the browser and fits naturally into modern documentation and development workflows.