draw.io
Free, no-account-needed diagramming that has become many engineering teams' default whiteboard.
What it is
About draw.io
draw.io (rebranded diagrams.net) is a free vector diagramming tool that runs in the browser or as a desktop app, with no mandatory account or cloud dependency — files can save to local disk, Google Drive, OneDrive or Confluence. It's widely used for system architecture diagrams, network topology, flowcharts, UML and ER diagrams because it's fast, free and produces clean, exportable diagrams. Its Confluence and VS Code plugins make it a common choice for embedding living architecture diagrams directly into documentation.
What you can do with it
Capabilities
Create flowcharts, network diagrams, UML, ER diagrams and organisation charts
Draw system and software architecture diagrams with a large shape library (AWS, Azure, GCP icons included)
Collaborate in real time when embedded in Confluence or via shared Drive links
Export to PNG, SVG, PDF or editable XML
Version diagrams alongside code by storing .drawio files in Git repositories
How to learn it
Learning Resources
Official diagrams.net documentation and template gallery
YouTube walkthroughs (search 'draw.io tutorial')
Practise by recreating an existing system's architecture diagram from scratch
Explore the built-in shape libraries for AWS, Azure and GCP architecture icons
Pro Tip
Store your .drawio files as XML text in the same Git repository as the code they describe — diagrams then get version history and pull-request review just like source code.
Skills that use this tool
Roles that use this tool