1. diagrams.net (previously draw.io) is a free online diagram drawing application for workflow, BPM, org charts, UML, ER, network diagrams. No login or registration are required and features include the ability to save locally (including SVG), a range of stencils, .
  2. Pencil is a standalone app or Firefox extension* that lets you create diagrams or UI mockups. It doesn't have collaboration/multi-user features.

    Discontinued

    It's Discontinued and no longer maintained.



  3. yEd is a powerful diagram editor that can be used to quickly create diagrams manually or import external data for analysis and auto-magically arrange even large data sets by just pressing a button.
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  4. Draw lets you produce anything from a quick sketch to a complex plan, and gives you the means to communicate with graphics and diagrams. With a maximum page size of 300cm by 300cm, Draw is a an excellent package for producing technical drawings, general posters, and much else.
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    • FreeOpen Source
    • Mac
    • Windows
    • Linux
    • PortableApps.com
    • FreeBSD
    • Xfce
    • DragonFly BSD
    • NetBSD
    • OpenBSD
    Dia is a GTK+ based diagram creation program for Linux, Unix, Mac OS X and Windows released under the GPL license.
  5. PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams. The generator can be run anywhere within JVM and integrated with various application such as wiki, text editor, IDE, programming language, documentation generator, and others.
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    • FreemiumProprietary
    • Online
    • Android
    • iPhone
    • Chrome OS
    • Android Tablet
    • iPad
    • Zapier
    • bambooHR
    • Amazon Web Services
    • Microsoft Office Powerpoint
    • Microsoft OneDrive
    • Jira
    • Microsoft Office Word
    • Google Drive
    • Slack
    • Google Drive - Docs
    • Quip
    • Microsoft Teams
    • Software as a Service (SaaS)
    • Salesforce.com
    • Google Apps
    • Microsoft Azure
    • Microsoft Office 365
    • Google Drive - Sheets
    • GitHub
    • Microsoft Office Suite
    • LinkedIn
    • Confluence
    • Microsoft Office Excel
    Lucidchart is a visual workspace that combines diagramming, collaboration, and data visualization to accelerate understanding and drive innovation. With this intuitive, cloud-based solution, everyone can work visually and collaborate in real time.
  6. Microsoft Office Visio makes it easy for IT and business professionals to visualize, explore, and communicate complex information. Go from complicated text and tables that are hard to understand to Visio diagrams that communicate information at a glance.
  7. Scalable, secure, cross-device and enterprise-ready team collaboration tool for distributed teams. BETTER TEAMS, BUILDING BETTER THINGS
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  8. Google Drawings, part of Google Drive, allows users to collaborate creating, sharing, and editing images or drawings. It can be used for creating charts, diagrams, designs, flow-charts, etc. It contains a subset of the features in...
  9. Visual Paradigm for UML (VP-UML) is a UML design tool and UML CASE tool designed to aid software development. VP-UML supports key modeling standards such as Unified Modeling Language (UML) 2.4, SysML, ERD, DFD, BPMN 2.0, ArchiMate 2.0, etc.
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    • FreeOpen Source
    • Mac
    • Windows
    • Linux
    • Online
    • Self-Hosted
    • JavaScript
    • Node.JS
    Ever wanted to simplify documentation and avoid heavy tools like Visio when explaining your code? This is why mermaid was born, a simple markdown-like script language for generating flowcharts, Gantt charts and sequence diagrams from text via JavaScript.
  10. Whimsical is a collaborative visual workspace for creating flowcharts, wireframes, virtual sticky notes, and more!.
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  11. Cacoo is a user-friendly online diagramming tool that allows you to create a variety of diagrams such as wireframes, flowcharts, UML diagrams, network diagrams, mindmaps, sitemaps, database diagrams, and more.
  12. "If they could see what Im thinking, they'd get it!" People just understand faster with pictures. It helps them see how information is connected, whether it is complete, and how a shift in one element impacts something else.