Convert JSON to Mermaid
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Converting JSON to Mermaid diagrams

Mermaid is a text-based diagramming language that renders flowcharts, sequence diagrams, and more in Markdown. GitHub, GitLab, and Notion render Mermaid automatically. This tool converts JSON structures into Mermaid diagram code, visualizing object relationships and hierarchies for documentation.

The converter generates Mermaid graph syntax from JSON. Objects become nodes, nested objects create edges, and arrays are represented as multiple connections. The code can be pasted into a Mermaid live editor, GitHub Markdown, or any tool supporting Mermaid rendering.

{
  "App": {
    "Frontend": ["React", "Redux"],
    "Backend": ["Node.js", "PostgreSQL"]
  }
}

graph TD
    App --> Frontend
    App --> Backend
    Frontend --> React
    Frontend --> Redux
    Backend --> Node.js
    Backend --> PostgreSQL

Get the most out of this tool

• GitHub renders Mermaid in Markdown: wrap output in ```mermaid code blocks for automatic visualization.
• Use Mermaid diagrams to visualize JSON relationships in API documentation and architecture records.
• Mermaid supports theming — add %%{init: {'theme':'dark'}}%% for dark mode rendering.

Mermaid diagrams from JSON data

Mermaid is a Markdown-inspired diagramming language that produces flow charts, sequence diagrams, class diagrams, entity-relationship diagrams, and more from plain text. GitHub, GitLab, Confluence, Notion, and many documentation platforms render Mermaid diagrams natively. Converting JSON data structures to Mermaid allows you to create visual representations of your data relationships directly from the data itself, without using separate diagramming tools.

JSON-to-Mermaid conversion produces entity-relationship (ER) diagrams or flowcharts depending on the input structure. A JSON object with nested objects produces an ER diagram where each object becomes an entity and object references become relationships. A JSON array of objects with cross-references (ID fields pointing to other records) produces a relational diagram showing how the data types connect. These diagrams are useful for communicating data models to team members unfamiliar with the raw JSON.

Mermaid ER diagram syntax uses the erDiagram keyword followed by entity definitions and relationship lines. An entity is defined as ENTITY_NAME { type field_name "description" ... }. Relationships are defined as ENTITY1 ||--o{ ENTITY2 : "relationship label" where the symbols encode cardinality: || is one, o{ is zero-or-more, |{ is one-or-more. The converter infers cardinality from array vs object reference relationships in the JSON structure.

Mermaid flowcharts are another output option for JSON data. A JSON state machine or workflow definition (with "states" and "transitions" keys, for example) naturally maps to a Mermaid flowchart where each state is a node and each transition is an edge. The converter detects common state machine JSON patterns and produces flowchart output instead of ER diagrams when the input looks like a graph or workflow definition.

GitHub renders Mermaid diagrams in Markdown code blocks with the language identifier "mermaid". Adding a Mermaid diagram to a GitHub README, Wiki, or issue requires only surrounding the Mermaid text with three backticks and the mermaid label. No image uploads, no external services — the diagram is rendered client-side by GitHub's Mermaid integration. This makes Mermaid the easiest way to include living, version-controlled diagrams in GitHub documentation.

Mermaid diagrams stay synchronized with your data when you regenerate them from the source JSON rather than manually editing SVG or PNG files. This "diagram as code" approach means your diagrams can be version-controlled alongside your code, reviewed in pull requests, and regenerated when the data structure changes. The converter is the bridge between your living JSON data model and the Mermaid diagram in your documentation.

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