Why D2’s 24K‑Star Open‑Source Diagram Tool Beats PlantUML and Drag‑Drop Editors

Problem Overview

Manual drag‑and‑drop diagram tools (draw.io, Visio) require minutes to align nodes and break when requirements change. Text‑based tools such as PlantUML produce chaotic layouts and need many obscure skinparam settings. Mermaid’s automatic layout fails after about ten nodes, and traditional tools like Graphviz emit cryptic error messages and have heavyweight environment dependencies, making CI‑based diagram generation difficult.

Tool Comparison

D2 – MPL 2.0, released 2022, implemented in Go, offline‑first, provides automatic code formatting, precise error reporting, built‑in professional themes, native Markdown support, animation, LaTeX embedding; cannot render directly on GitHub.

Mermaid – MIT, released 2015, JavaScript‑based, requires GitHub rendering, lacks auto‑formatting and precise errors, offers built‑in themes and Markdown support but no animation or LaTeX.

PlantUML – GPL 3.0, released 2009, Java‑based, works offline, but has no auto‑formatting, precise errors, or built‑in themes, and cannot render on GitHub.

Graphviz (DOT) – EPL 1.0, released 1991, written in C, works offline, but provides none of the modern conveniences listed above.

Core Advantages of D2

Simple syntax : Indentation defines hierarchy (YAML‑like). A one‑line example x -> y -> z creates a directed graph instantly.

Three built‑in layout engines :

Dagre (default) – layered layout for most flowcharts.

ELK (default) – optimized for complex network topologies and micro‑service diagrams.

TALA (self‑developed) – best‑in‑class layout for large enterprise diagrams; the free version offers clipping, the Pro version adds advanced features.

Professional themes : Hundreds of designer‑crafted light, dark, business, and minimalist themes switchable with a single theme-id line.

Animation & LaTeX : The only text‑based tool that can generate animated SVGs and embed native LaTeX formulas.

Precise error handling : The parser reports line numbers, error type, and suggested fixes, and continues checking the whole file instead of aborting at the first issue.

Automatic code formatting : Saving a file automatically normalizes indentation and style.

Ecosystem : Official plugins for VSCode, Vim, Obsidian and community plugins for Emacs, Confluence, Maven, Pandoc, etc., provide syntax highlighting, auto‑completion, and live preview.

Zero‑dependency binary : Compiled from Go into a single executable; runs on Windows, macOS, and Linux without Java, browsers, or other runtimes, simplifying CI/CD integration.

Git‑friendly : Diagrams are plain text, enabling version control, diffing, and automated generation from schemas in CI pipelines.

Installation & Quick‑Start

Install with one of the following methods:

curl -fsSL https://d2lang.com/install.sh | sh -s --

brew install d2

go install oss.terrastruct.com/d2@latest

powershell winget install terrastruct.D2

Verify installation: d2 version Create a file hello.d2 containing x -> y -> z and watch it live‑update: d2 --watch hello.d2 out.svg Online Playground (no installation required): https://play.d2lang.com

Current Limitations

No native GitHub README rendering; work‑arounds involve CI actions that generate SVGs and commit them.

Built‑in icon library is smaller than draw.io’s extensive cloud‑service icons.

Advanced TALA layout features require the paid Pro version.

Automatic layout sacrifices pixel‑level positioning; precise manual placement is not possible.

Very large graphs (many nodes and deep nesting) compile slower, though typical medium‑size diagrams are unaffected.

Tool‑Selection Guidance

Prefer D2 for backend architects, engineering teams, and anyone needing version‑controlled, CI‑friendly, animated or LaTeX‑rich diagrams.

Prefer Mermaid for open‑source projects that need quick Markdown diagrams rendered directly on GitHub.

Prefer PlantUML for legacy Java ecosystems focused on sequence diagrams.

Prefer draw.io / Visio when pixel‑perfect layout, extensive icon sets, or high‑fidelity UI mockups are required.

Conclusion

D2 fills gaps left by traditional text‑based diagram tools: it offers an engineering‑oriented workflow, beautiful default output, rich extensibility, and automation‑ready design, turning architecture diagrams from static snapshots into maintainable code assets.

https://github.com/terrastruct/d2