One of the most popular alternatives to Dia is draw.io, which is free and open source. Other popular alternatives are Excalidraw, LibreOffice - Draw, yEd Graph Editor and Lucidchart. There's no shortage of Diagram Editors like Dia, with more than 50 alternatives for Windows, the web, Mac, Linux and iPad.
Feature-rich, open-source Wireflow offers a collaborative platform for online creation of complex user flow prototypes. Ideal for team work in UI design, wireframing, and mind mapping, promoting idea sharing in real-time environment aided by modern whiteboard features.
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.
United States
Creates diagrams from textual descriptions! It provides a unified API with support for BlockDiag, BPMN, Bytefield, C4 (with PlantUML), Ditaa, Erd, GraphViz, Mermaid, Nomnoml, PlantUML, SvgBob, UMLet, Vega, Vega-Lite, WaveDrom.
Free vector graphics editor offering real-time collaborative editing, browser and cross-platform desktop support, scalable design tools, AI, EPS, SVG, PNG, JPEG import/export, grouping and shape manipulation, and intuitive pen and freehand drawing options.
Singapore
Mindomo is the easiest online software for creating mind maps, concept maps, outlines and various other types of diagrams. The following features make it the perfect choice both for business and education:
Romania
EU
Gaphor is a WYSIWYG (What You See Is What You Get) UML and SysML modeling environment easy to use that will help you create your applications.
NetherlandsEU
Umbrello is a Unified Modelling Language (UML) modelling tool and code generator. It can create diagrams of software and other systems in the industry-standard UML format, and can also generate code from UML diagrams in a variety of programming languages.
GermanyEU
Heimer is a desktop application for creating mind maps and other suitable diagrams. It's written in Qt and targeted for Linux and Windows.
Draw, part of the Apache OpenOffice suite, is a graphics editor that gives you the tools to communicate with visuals and diagrams. With a maximum page size of 300cm by 300cm, Draw is powerful tool for posters, graphs, charts, and more.
United States
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.
United States
Instead of starting with a blank screen, SmartDraw gives you the exact template you need. Then use simple commands to add your information and SmartDraw does the rest. There's no other drawing software like it.
United States
Lightweight, powerful, easy to use, UML tool
Software Ideas Modeler is a lightweight and powerful CASE tool. It supports UML 2.2 diagrams and a lot of other ones. Software Ideas Modeler is freeware (for non-commercial use). Commercial user may use this software only after buying.
SlovakiaEU
