Skip to main content
Block diagrams provide an intuitive way to represent complex systems, processes, or architectures visually. They are composed of blocks and connectors, where blocks represent fundamental components and connectors show relationships between them.

Introduction

Block diagrams give you full control over where shapes are positioned, unlike flowcharts where automatic layout can move shapes unexpectedly.

Basic syntax

Simple blocks

Create a basic block diagram with three blocks:

Columns

Organize blocks into columns: This creates a 3-column layout where ‘d’ wraps to the second row.

Advanced configuration

Block width

Span blocks across multiple columns: Blocks ‘b’ and ‘c’ each span 2 columns.

Composite blocks

Create nested blocks:

Complex layouts

Combine column widths and composite blocks:

Vertical stacking

Stack blocks vertically using a single column:

Block shapes

Round edged

Stadium shaped

Subroutine

Cylindrical (database)

Circle

Asymmetric

Rhombus

Hexagon

Parallelogram and trapezoid

Double circle

Block arrows and spaces

Block arrows

Indicate directional flow:

Space blocks

Create intentional empty spaces: Or specify width:

Connecting blocks

Complete example

Styling

Individual block styling

Class styling

Define reusable styles:

Practical examples

System architecture

Business process flow

Tips and best practices

Use comments with %% to document your diagram structure, especially when working in teams.
Break down complex diagrams into smaller, modular components for easier maintenance.
Ensure links between blocks use correct arrow syntax (--> or ---) and remember to add space blocks between connected blocks for proper positioning.
When applying styles, separate properties with commas and use proper CSS property format: style A fill:#969,stroke:#333;

Build docs developers (and LLMs) love