# D2 — Text-to-Diagram Scripting Language for Developers

> D2 is a declarative diagram scripting language that turns text into diagrams. It supports various layout engines and output formats, letting developers create and maintain complex diagrams as code.

## Install

Save as a script file and run:

# D2 — Text-to-Diagram Scripting Language for Developers

## Quick Use

``````bash
# Install via Homebrew
brew install d2

# Create a diagram file
echo 'x -> y -> z' > hello.d2

# Render to SVG
d2 hello.d2 hello.svg

# Watch mode for live editing
d2 --watch hello.d2 hello.svg
``````

## Introduction

D2 is a modern, declarative diagramming language developed by Terrastruct. You write text descriptions and D2 compiles them into SVG, PNG, or PDF output. It focuses on readability, making diagrams easy to version-control alongside code.

## What D2 Does

- Compiles ``.d2`` text files into SVG, PNG, and PDF diagrams with automatic layout
- Supports multiple layout engines including dagre, ELK, and TALA
- Provides containers, connections, shapes, icons, and markdown labels
- Includes watch mode that live-reloads rendered output as you edit
- Handles sequence diagrams, class diagrams, and ER diagrams natively

## Architecture Overview

D2 is written in Go and operates as a CLI compiler. Source files are parsed into an AST, processed through a pluggable layout engine, then rendered to the chosen output format. Open-source layout engines dagre and ELK are bundled; the TALA engine is an optional proprietary add-on.

## Self-Hosting & Configuration

- Install from source with ``go install oss.terrastruct.com/d2`` or use prebuilt binaries
- Configure layout engine, theme, and output format via CLI flags
- Built-in themes are selectable by name; dark-mode variants included
- Embed D2 in CI pipelines to auto-generate diagrams on each commit
- Use the VS Code extension for syntax highlighting and inline preview

## Key Features

- **Declarative syntax**: readable, indentation-based text format
- **Multiple output formats**: SVG, PNG, and PDF from the same source
- **Pluggable layouts**: choose dagre, ELK, or TALA per diagram
- **Sequence diagrams**: first-class lifelines and message arrows
- **Markdown labels**: inline markdown for rich text inside shapes

## Comparison with Similar Tools

- **Mermaid**: browser-native, widely embedded in doc platforms; D2 offers more layout control
- **PlantUML**: mature UML focus; D2 has cleaner syntax and faster rendering
- **Graphviz**: classic graph layout tool; D2 provides modern syntax and better defaults
- **Excalidraw**: hand-drawn canvas editor; D2 is text-first and version-control friendly

## FAQ

**Q: Is D2 free and open source?**
A: Yes, under the MPL-2.0 license. The TALA layout engine is a separate proprietary option but not required.

**Q: Can I use D2 in CI/CD pipelines?**
A: Yes. D2 is a standalone CLI binary that integrates into any CI pipeline.

**Q: Does D2 support dark mode?**
A: Yes, D2 ships with multiple themes including dark-mode variants.

**Q: How does D2 compare to Mermaid?**
A: Mermaid renders in-browser and is natively supported by GitHub. D2 produces higher-quality output with more layout options but requires a build step.

## Sources

- Repository: https://github.com/terrastruct/d2
- Documentation: https://d2lang.com/tour/intro

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Source: https://tokrepo.com/en/workflows/asset-e6fd929c
Author: Script Depot