D2 Review, Pricing & Features

D2 is a free, open-source diagram scripting language by Terrastruct that turns text into architecture diagrams. See features, licensing and alternatives.

Researched and fact-checked by Bartu Cavusoglu · Updated July 18, 2026

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Category
Collaboration
Pricing
Free / Open Source, from Free
Verified
Not yet
Last updated
July 18, 2026
Founded
2022
Headquarters
San Francisco, California, USA
Free PlanWindowsAPIOpen SourceSelf-HostedMac

Overview

D2 is an open-source declarative diagram scripting language created by Terrastruct, a San Francisco company founded in 2019 by Alexander Wang. Terrastruct open-sourced D2 in November 2022 under the Mozilla Public License 2.0.

D2 lets users describe diagrams as plain text, which an automatic layout engine then renders as SVG, PNG or PDF, making it part of the growing diagrams-as-code category alongside Mermaid and PlantUML.

Key Features

D2 offers multiple auto-layout engines, including dagre and an ELK-based engine, a shape library tuned for software architecture (cylinders, queues, clouds, person icons), and several built-in visual themes including dark mode.

Because diagrams are plain text files, they can be stored in Git, diffed, and code-reviewed like any other source file, with tooling including an autoformatter, multi-error parser, syntax highlighting, and editor integrations for VS Code, Vim and Obsidian.

Pricing

The D2 language and command-line compiler are entirely free and open source, with no cost to download, run, or embed in personal or commercial projects.

Terrastruct's revenue comes from a separate paid diagramming application built around D2 that adds visual editing and real-time collaboration for teams, funding continued development of the open-source language.

Key Features

Pros & Cons

Pros

  • Completely free and open source (MPL-2.0)
  • Diagrams stored as plain text, ideal for Git version control and code review
  • Purpose-built shape library and layout for software architecture diagrams
  • Active open-source community and growing ecosystem of integrations

Cons

  • Newer and less pre-integrated into platforms like GitHub or Notion than Mermaid
  • Requires learning a diagram-specific syntax rather than pure drag-and-drop
  • Advanced visual and collaborative editing requires Terrastruct's separate paid app
  • Auto-layout engines can require manual tuning for very complex diagrams

Pricing

Frequently Asked Questions

Is D2 free?

Yes, the D2 language and command-line tool are free and open source under the Mozilla Public License 2.0.

Who created D2?

D2 was created by Terrastruct, a San Francisco-based company founded in 2019 by Alexander Wang.

What license is D2 released under?

D2 is licensed under the Mozilla Public License 2.0 (MPL-2.0).

How is D2 different from Mermaid?

D2 offers a more customizable visual output and an architecture-focused shape library, while Mermaid has broader native integration into platforms like GitHub and Notion.

Can I use D2 without installing anything?

Yes, D2 can be used via Terrastruct's hosted playground or editor, though the CLI tool can also be installed for local use.

Does Terrastruct sell a paid product built on D2?

Yes, Terrastruct offers a separate paid diagramming application with visual editing and collaboration features built around the D2 language.

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