Diagram as Code: A Practical Guide to Mermaid in 2026

Why Diagram as Code?

Traditional diagramming tools require a visual editor — you drag shapes, draw lines, and save binary files. This works for one-off diagrams, but it breaks down when diagrams need to:

• Live alongside code in version control (Git-friendly diffs)
• Be reviewed in pull requests like any other documentation
• Stay in sync with the codebase they describe
• Be generated or updated programmatically

Mermaid solves all of these by treating diagrams as code. You write text, and the renderer produces the visual output.

What You Can Build

Mermaid supports a wide range of diagram types:

• Flowcharts — Decision trees, process flows, algorithms
• Sequence diagrams — API calls, service interactions, protocols
• Class diagrams — Object relationships, inheritance hierarchies
• ER diagrams — Database schema visualization
• Gantt charts — Project timelines and task dependencies
• State diagrams — State machines, lifecycle modeling
• Git graphs — Branch visualization (added in recent versions)
• Mindmaps — Brainstorming and idea organization

Platform Support in 2026

One of Mermaid's biggest strengths is its ecosystem. It's now natively supported on most platforms where developers write documentation:

A Quick Syntax Example

Here's how simple it is to create a flowchart in Mermaid:

graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Action 1]
    B -->|No| D[Action 2]
    C --> E[End]
    D --> E

This text gets rendered as a top-down flowchart with a decision diamond and two branches. No dragging, no alignment — just text.

Converting Mermaid to Other Formats

While Mermaid is great for documentation, there are times you need a visual format — a .drawio file for Confluence, an .svg for a presentation, or an .excalidraw file for further editing.

Orriguii Diagram Converterhandles these conversions. Drop a .mmd file, pick your target format, and download the result. The converter maps Mermaid's nodes and edges to the equivalent shapes and connectors in Excalidraw or Draw.io.

Tips for Effective Mermaid Diagrams

• Keep diagrams focused — One diagram per concept. If it needs scrolling, split it.
• Use meaningful node IDs — AuthService is better thanA for readability.
• Add labels to edges — Arrows without labels are ambiguous.
• Version your diagrams— Since they're text, they get full Git history for free.