Text-based diagram rendering helps teams maintain architecture visuals in the same workflow as code and documentation.
Use this workspace like a mini app: enter input, review output, run examples, and copy or download results.
Mermaid Viewer is designed for quick, repeatable workflows. Start with an example, verify output, then adapt for your own data.
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Search intent this page covers
This page is optimized for practical engineering intent: fast in-browser transformation, inspection, and debugging workflows.
Relevant developer queries include mermaid viewer, mermaid live editor, render mermaid diagram online. Use this tool for rapid checks, then continue with related tools for deeper analysis.
Mermaid Viewer lets you turn text-based Mermaid syntax into rendered diagrams without switching to another application. You can write or paste Mermaid source, render the output in a dedicated preview workspace, and quickly iterate on technical diagrams while editing documentation or architecture notes. Mermaid works by using different syntaxes for different diagram types, so a flowchart, sequence diagram, class diagram, and ER diagram each have their own grammar. This page helps you test those syntaxes with immediate visual feedback and explicit error messages when a diagram fails to parse. It is useful for developers who keep diagrams close to code and docs because Mermaid source is version-control friendly, searchable, and easy to review in pull requests. The viewer includes practical presets so you can start from working examples, copy source when sharing with teammates, and export SVG output for docs that need static assets. This tool focuses on rendering Mermaid in-browser and does not claim features like collaborative editing, diagram storage, or advanced layout controls beyond what Mermaid itself provides.
When developers use this tool
Text-based diagram rendering helps teams maintain architecture visuals in the same workflow as code and documentation.
Developers typically use Mermaid Viewer for workflows such as Preview Mermaid blocks used in Markdown or docs repositories, Draft architecture flows and API interactions for technical reviews, Render class and ER diagrams from source before publishing docs. It is especially useful when you need to When documenting systems with version-controlled diagram source, When validating Mermaid syntax before committing documentation updates, When you need quick SVG diagram output from text definitions without leaving the browser.
Mermaid Viewer is commonly used during day-to-day debugging, data cleanup, and integration work. Review the scenarios below to decide when it fits your workflow.
Use these checkpoints to choose the right moment for this utility and avoid repetitive manual formatting.
Load a sample to validate input/output structure, then adapt it to your own data.
Flowchart example
Input sampleflowchart TD
A[Start] --> B{Feature flag enabled?}
B -->|Yes| C[Serve new experience]
B -->|No| D[Serve fallback]
C --> E[Done]
D --> EOutput previewRendered flowchart with decision branches and terminal state.
Sequence example
Input samplesequenceDiagram participant Client participant API participant DB Client->>API: GET /projects API->>DB: Query projects DB-->>API: Rows API-->>Client: 200 JSONOutput preview
Rendered sequence diagram showing request and response order.
Quick answers for common implementation and usage questions.
Each diagram category has its own grammar, so flowchart keywords differ from sequence or class diagram keywords.
It renders Mermaid source using the Mermaid runtime in-browser and reports parse errors, but advanced behavior depends on the Mermaid version and supported syntax.
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