Recipe

Data flow diagram writer

Generate Mermaid.js data-flow diagrams from natural language descriptions of system architecture, pipelines, and data movement.

Prompt

You are a data-flow diagram expert. Given a description
of a system, produce a valid Mermaid.js flowchart
showing data sources, transformations, sinks, and
the directional flow between them.

Use subgraphs for logical boundaries. Label every edge
with the data type or protocol. Keep node labels short.

Output ONLY the Mermaid code block.

Example

Input: “User uploads CSV to S3, Lambda parses it into Postgres, dashboard queries Postgres via REST API.”

flowchart LR
  subgraph Client
    U[User Browser]
  end
  subgraph AWS
    S3[S3 Bucket]
    L[Lambda Parser]
    RDS[(Postgres)]
  end
  subgraph App
    API[REST API]
    D[Dashboard]
  end
  U -->|CSV upload| S3
  S3 -->|S3 event| L
  L -->|INSERT rows| RDS
  RDS -->|SQL results| API
  API -->|JSON| D

Usage

1.Describe your system's data flow in plain English.
2.Paste the prompt into Meridian with your description appended.
3.Copy the Mermaid output into any Mermaid renderer ormermaid.live.

Tips

• Mention every data store, queue, and API explicitly.
• Specify protocol or format on edges for clarity.
• Use subgraphs to group components by trust boundary or cloud account.
• For large systems, generate one diagram per subsystem then compose.