merman-cli

merman-cli is the command-line interface for merman. It can detect, parse, layout, and render Mermaid diagrams without a browser.

Install

cargo install merman-cli

From a local checkout:

cargo install --path crates/merman-cli

Commands

merman-cli detect path/to/diagram.mmd
merman-cli parse --pretty --meta path/to/diagram.mmd
merman-cli layout --pretty path/to/diagram.mmd
merman-cli render path/to/diagram.mmd --out out.svg
merman-cli render --format png --out out.png path/to/diagram.mmd
merman-cli render --format jpg --out out.jpg path/to/diagram.mmd
merman-cli render --format pdf --out out.pdf path/to/diagram.mmd

If no input path is provided, or the input path is -, merman-cli reads Mermaid source from stdin.

printf "flowchart TD\nA[API] --> B[DB]\n" | merman-cli render --out out.svg

Rendering Options

render writes SVG to stdout by default. Use --out for files and --format png|jpg|pdf for raster or PDF export.

Useful flags:

• --text-measurer deterministic|vendored controls text measurement. vendored is better for visual output; deterministic is useful for stable fixture-style output.
• --id <diagram-id> sets the root SVG id and internal marker id prefix.
• --scale <n> controls PNG/JPG raster scale.
• --background <css-color> sets raster background.
• --hand-drawn-seed <n> stabilizes rough/hand-drawn rendering where supported.
• --viewport-width <w> and --viewport-height <h> configure viewport-sensitive layouts.
• --suppress-errors emits an error diagram instead of failing on parse errors.

SVG Input Rasterization

merman-cli render --format png|jpg|pdf can also rasterize existing SVG input when the input starts with <svg.

merman-cli render --format png --out diagram.png diagram.svg

The raster path applies merman's resvg-safe SVG cleanup before conversion.