draw.io — Free Diagramming Tool for Architecture and Flowcharts

Introduction

draw.io (also known as diagrams.net) is a free diagramming tool that runs entirely in the browser or as a desktop application. It supports a wide range of diagram types including flowcharts, UML, ER diagrams, network topologies, and cloud architecture diagrams, with direct integrations into Confluence, Jira, Google Drive, and VS Code.

What draw.io Does

• Creates flowcharts, UML diagrams, ER diagrams, BPMN, network diagrams, and cloud architecture visuals
• Provides hundreds of built-in shape libraries including AWS, Azure, GCP, Cisco, and Kubernetes icons
• Stores diagrams in editable XML format compatible with version control systems
• Integrates with Confluence, Jira, Google Drive, OneDrive, GitHub, and GitLab
• Exports to PNG, SVG, PDF, VSDX (Visio), and HTML formats

Architecture Overview

draw.io is a client-side JavaScript application built on the mxGraph library (now part of the project). All diagram rendering and editing happens in the browser with no server-side processing of diagram data. The desktop version wraps the web app in Electron. Storage is pluggable: diagrams can be saved to local disk, Google Drive, OneDrive, Dropbox, GitHub, or GitLab. The self-hosted Docker image serves the static web app without handling any user data server-side.

Self-Hosting & Configuration

• Deploy the Docker image to serve the web app from your own infrastructure
• Configure storage backends for Google Drive, OneDrive, or local file system
• Embed draw.io in Confluence Server/Cloud or Jira via official plugins
• Use the VS Code extension for editing diagrams alongside code in your IDE
• Customize shape libraries and templates for your organization

Key Features

• No account required and no diagram data sent to external servers in self-hosted mode
• Extensive shape libraries covering cloud providers, networking, UML, and general flowcharting
• Real-time collaboration when using cloud storage backends like Google Drive
• Diagram-as-code support with CSV, SQL, and text-based import for automated diagram generation
• Offline-capable desktop app for air-gapped environments

Comparison with Similar Tools

• Lucidchart — SaaS with subscription pricing; draw.io is free with no feature limits
• Visio — Microsoft commercial tool; draw.io is open-source and cross-platform
• Mermaid — text-based diagram rendering; draw.io provides a visual drag-and-drop editor
• Excalidraw — sketch-style whiteboard; draw.io focuses on precise technical diagrams
• PlantUML — code-based UML; draw.io offers both visual editing and code import

FAQ

Q: Is draw.io really free? A: Yes. The web app, desktop app, and self-hosted Docker image are completely free. Revenue comes from Confluence and Jira plugin licensing.

Q: Can I use it offline? A: Yes. The desktop app works fully offline. The web version requires initial loading but can work offline afterward with local storage.

Q: Does self-hosting require a backend server? A: No. The Docker image serves static files only. All processing happens in the browser.

Q: Can I store diagrams in Git? A: Yes. Diagrams are saved as XML files that diff and merge well in version control systems.

Sources

• https://github.com/jgraph/drawio
• https://www.drawio.com