Diagramming software is a computer program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

 that is used to produce graphical diagrams. Diagrams are used in software and business to represent dataflows

Data flow diagram

A data flow diagram is a graphical representation of the "flow" of data through an information system, modelling its process aspects. Often they are a preliminary step used to create an overview of the system which can later be elaborated...

, workflow

Workflow

A workflow consists of a sequence of connected steps. It is a depiction of a sequence of operations, declared as work of a person, a group of persons, an organization of staff, or one or more simple or complex mechanisms. Workflow may be seen as any abstraction of real work...

s and software architecture

Software architecture

The software architecture of a system is the set of structures needed to reason about the system, which comprise software elements, relations among them, and properties of both...

.

Flowchart

Flowchart

A flowchart is a type of diagram that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting these with arrows. This diagrammatic representation can give a step-by-step solution to a given problem. Process operations are represented in these...

 

• ARIS Express
  ARIS Express
  ARIS Express is a free-of-charge modeling tool for business process analysis and management. It supports different modeling notations such as BPMN 2, Event-driven Process Chains , Organizational charts, process landscapes, whiteboards, etc. ARIS Express was initially developed by IDS Scheer, which...
  
   (freeware
  Freeware
  Freeware is computer software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights. Freeware is in contrast to commercial software, which is typically sold for profit, but might be distributed for a business or commercial purpose in the...
  
  )
• Creately
  Creately
  Creately is a cloud-based diagramming and design application service operated by Cinergix, Pty Ltd. It is built on Adobe's Flex/Flash technologies and provides a visual communication platform for virtual teams...
  
  
• ConceptDraw Office
• Dia (open source
  Open source
  The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
  
  )
• Diagram Designer
  Diagram Designer
  Diagram Designer is a free flowchart creating software designed by Michael Vinther. It can also create diagrams and slideshows.-Features:* Customizable template object palette.* Spellchecker....
  
  
• DiamFC
• Graphviz
  Graphviz
  Graphviz is a package of open-source tools initiated by AT&T Labs Research for drawing graphs specified in DOT language scripts. It also provides libraries for software applications to use the tools...
  
   (open source
  Open source
  The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
  
  )
• Inkscape
  Inkscape
  Inkscape is a free software vector graphics editor, licensed under the GNU General Public License. Its goal is to implement full support for the Scalable Vector Graphics 1.1 standard....
  
   (open source
  Open source
  The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
  
  )
• Inspiration
  Inspiration Software
  Inspiration® Software, Inc. is an education technology software company based in Portland, Oregon, which provides several visual thinking and learning products for the K-12 education and business markets including Inspiration®, InspireData®, Kidspiration®, Webspiration Classroom™ service and...
  
  
• Calligra Flow (formerly Kivio) (open source
  Open source
  The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
  
  )
• LucidChart
  LucidChart
  LucidChart is a web-based diagramming software. This software is notable because it is built on web standards such as HTML5 and Javascript and provides real-time collaboration for the creation of graphical content...
  
  
• Microsoft Visio
  Microsoft Visio
  Microsoft Visio , formerly known as Microsoft Office Visio, is a commercial diagramming program for Microsoft Windows that uses vector graphics to create diagrams.- Features :...
  
  
• OmniGraffle
  OmniGraffle
  OmniGraffle is a diagramming application made by The Omni Group. OmniGraffle is built only for Mac OS X and the iPad. It may be used to create diagrams, flow charts, org charts, and illustrations. It features a drag-and-drop WYSIWYG interface...
  
  
• OpenOffice.org Draw
  OpenOffice.org Draw
  OpenOffice.org Draw is a vector graphics editor and is part of the OpenOffice.org office suite. It features "connectors" between shapes, which are available in a range of line styles and facilitate building drawings such as flowchart...
  
   (open source
  Open source
  The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
  
  )
• Schematic
  Schematic (software)
  Schematic is an application for creating schematic diagrams, such as flow charts, organisation charts, electronic circuit diagrams, UML and family trees. It is published and actively maintained by Dot Software Ltd in Bath, England....
  
  
• SmartDraw
  SmartDraw
  SmartDraw is a visual processor used to create flowcharts, organization charts, mind maps, project charts, and other visuals. SmartDraw is built exclusively for Windows operating systems and works with Windows 7, Vista, XP, and 2000...
  
  
• StarOffice
  StarOffice
  StarOffice, known briefly as Oracle Open Office before its discontinuation in 2010, is a proprietary office suite. It was originally developed by StarDivision which was acquired by Sun Microsystems in 1999...
  
  
• XCircuit
  Xcircuit
  XCircuit is a Unix/X11 program for drawing publishable-quality electrical circuit schematic diagrams and related figures, and produce circuit netlists through schematic capture. XCircuit regards circuits as inherently hierarchical, and writes both hierarchical PostScript output and hierarchical...
  
  
• yEd
  YEd
  yEd is a freely available, general-purpose diagramming software with amulti-document interface.It is a cross-platform application written in Java that runs on Windows, Linux, Mac OS, or any platform that supports the JVM....
  
   (freeware
  Freeware
  Freeware is computer software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights. Freeware is in contrast to commercial software, which is typically sold for profit, but might be distributed for a business or commercial purpose in the...
  
  )

Concept mapping/Mind mapping 

Concept mapping and mind mapping are a subset of diagramming software aimed to represent collections of ideas.

Online diagramming

Online diagramming is a way to create flow charts and business diagrams without having to download and install any software. The diagram will be created completely online and is then exported as an image or pdf file.

Online Drawing tools

• Cacoo
  Cacoo
  Cacoo is an Adobe Flash-based real-time collaborative diagramming application created by the Fukuoka, Japan based Nulab Inc. Cacoo features a large stencil set that allows users to create site maps, wireframes, flowcharts, network diagrams, mind maps, UML diagrams and others.Diagrams created using...
  
   - Online Real-Time Collaborative Diagramming & Drawing. Flash-based.
• Creately
  Creately
  Creately is a cloud-based diagramming and design application service operated by Cinergix, Pty Ltd. It is built on Adobe's Flex/Flash technologies and provides a visual communication platform for virtual teams...
  
   - Online Diagramming & Design. Relatively new competitor of Gliffy. Flash-based.
• Diagramly - Free Online Diagramming application. Standards-based, uses HTML, JavaScript and XML. Created by writers of JGraph
  Jgraph
  JGraph is a graph drawing open source software component written in the Java programming language; started by Gaudenz Alder as a University project in 2000 at ETH Zurich, Switzerland.-History:...
  
  
• Graphity - Free online diagramming application. Flash-based. Created by the makers of yEd
  YEd
  yEd is a freely available, general-purpose diagramming software with amulti-document interface.It is a cross-platform application written in Java that runs on Windows, Linux, Mac OS, or any platform that supports the JVM....
  
  .
• LucidChart
  LucidChart
  LucidChart is a web-based diagramming software. This software is notable because it is built on web standards such as HTML5 and Javascript and provides real-time collaboration for the creation of graphical content...
  
   - Online Real Time Collaborative Diagramming & Flowchart Software. Uses only web standards like HTML5 and Javascript. Non-flash-based.
• SpicyNodes
  SpicyNodes
  In concept mapping and information visualization, SpicyNodes is a method for displaying hierarchical data in which a focus node displays rich information, and the surrounding nodes display related information .- Main idea :...
  
  - Radial tree visualizer with a drag-and-drop hierarchical tree editor, which generates interactive, radial tree diagrams.