Getting started

Mermaider renders Mermaid diagram syntax to sanitized SVG in pure .NET — no JavaScript runtime, no headless browser, no subprocess.

dotnet add package Mermaider
		

Targets net8.0 and later. No transitive native or JavaScript dependencies.

using Mermaider;

string svg = MermaidRenderer.RenderSvg("""
    flowchart LR
      A[Parse] --> B[Layout] --> C[Render SVG]
""");

// svg is a complete, sanitized SVG string — embed it directly in HTML
Response.Write(svg);
		

RenderSvg returns a self-contained SVG string. Write it into your HTML response, save it to disk, or pipe it anywhere — no further processing needed.

// Write SVG bytes directly to an HTTP response stream
await MermaidRenderer.RenderSvgAsync(diagram, Response.Body, cancellationToken: ct);

// Or to a PipeWriter for zero-copy scenarios
await MermaidRenderer.RenderSvgAsync(diagram, pipeWriter, cancellationToken: ct);
		

The CancellationToken is honored throughout the full parse → layout → render pipeline, not only on the final write.

Pass a RenderOptions record to control colors, fonts, layout, and security behavior:

var options = new RenderOptions
{
    Bg = "#0D1117",
    Fg = "#E6EDF3",
    Accent = "#58A6FF",
    Font = "Inter",
    Transparent = true,
    Strict = new StrictStylingOptions()
};

string svg = MermaidRenderer.RenderSvg(diagram, options);
		

See Theming for the full color token reference, and Security for strict mode and sanitization options.

MermaidResourceLimitException is a subtype of MermaidParseException — existing catch (MermaidParseException) blocks automatically cover limit violations.

MermaidRenderer is a static class. RenderSvg is thread-safe — call it concurrently from as many threads as you like. Internal ObjectPool<StringBuilder> instances are shared across calls.