LibreOffice - Draw!

Lucidchart is an online diagram and flowchart software that supports Microsoft Office Visio import and can work on any operating system. The easiest way to draw flowcharts, wireframes, UML diagrams, network diagrams, mind maps, iPhone mockups, site maps and more. Work together in real time with your team and clients! Along with the online version, Lucidchart also has a downloadable solution that runs on Mac, Windows and Linux; this enables offline editing at any time! »

An Open Source vector graphics editor, with capabilities similar to Illustrator, CorelDraw, or Xara X, using the W3C standard Scalable Vector Graphics (SVG) file format.

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, .vsdx, Lucidchart and Gliffy import and real time diagram sharing.

Pencil is a standalone app or Firefox extension that lets you create diagrams or UI mockups. It doesn't have collaboration/multi-user features.

Design quickly and confidently with Adobe Illustrator software. Sophisticated tools for drawing and typography, along with advanced color controls and creative effects, provide a comprehensive vector graphics environment. Explore more efficient ways of working with multiple artboards, a Blob Brush tool for intuitive vector painting, and transparency in gradients with on-object controls. Stay ahead of the pace of change — equip yourself with precisely the tools you need for today’s print, web, interactive, motion, and mobile content design. »

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. You can use yEd to quickly create flow charts, BPMN and UML diagrams, organization charts, mind maps, and many other kinds of diagrams, graphs, and networks. Choose from a wide range of highly sophisticated layout algorithms to automatically arrange diagrams in no time. An intuitive and visually appealing user interface makes creating diagrams fun. Once a diagram has been created, it’s easy to save, print, or export it to popular formats like PDF, SWF, EMF, SVG, JPEG, GIF, PNG, or HTML image maps. »

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. Instead of static pictures, create data-connected Visio diagrams that display data, are easy to refresh, and dramatically increase your productivity.

Lucidchart is an online diagram and flowchart software that supports Microsoft Office Visio import and can work on any operating system. The easiest way to draw flowcharts, wireframes, UML diagrams, network diagrams, mind maps, iPhone mockups, site maps and more. Work together in real time with your team and clients! Along with the online version, Lucidchart also has a downloadable solution that runs on Mac, Windows and Linux; this enables offline editing at any time! »

MindMeister is the market-leader in online mind mapping. Unlike traditional mind mapping tools, MindMeister allows for real-time brainstorming sessions between an unlimited number of users and requires only a standard web browser.MindMeister's intuitive editor is perfect for taking notes, brainstorming ideas, planning projects and outlining all sorts of texts. Users can choose between the classical mind map layout and org chart mode, and can export their mind maps into various formats like MS Word, PowerPoint, PDF, PNG etc. With its built-in presentation mode, users can also turn their mind maps into slideshows within seconds, and present them on the big screen or broadcast them to their collaborators. »

Clip Studio Paint, previously Manga Studio or ComicStudio in Japan, is a family of software applications for Mac OS X and Microsoft Windows used for the digital creation of comics and manga.

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.

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 Google Drive - Slides but with different templates. Its features include laying out drawings precisely with alignment guides, snap to grid, auto distribution, and inserting drawings into other Google documents, spreadsheets, or presentations. »

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:* real-time collaboration* you can work on maps even if your internet connection is down, and your changes will be automatically synchronized when the connection is restored* playback mode that shows you how a map was built* maps can be turned into presentations or real-time editable outlines* Google Apps and various LTI integrations (Canvas, Moodle, Blackboard, Desire2Learn, itslearning)* great variety of exports (PDF, RTF, PPT, TXT, OPML, MPX, HTML, ZIP, PNG, XLS, MOM, MM, MMAP)* Google Drive, Dropbox, FTP and ZIP backups »

Boxy SVG is a vector graphics editor simillar to Adobe Illustrator, Sketch and Inkscape. Made with and for the modern Web Platform. Can do illustrations, icons, banners, mockups, charts, buttons and more.

OmniGraffle can help you make eye-popping graphic documents—quickly—by providing powerful styling tools, keeping lines connected to shapes even when they’re moved, and magically organizing diagrams with just one click. Create flow charts, diagrams, UI and UX interactions, and more. Whether you need a quick sketch or an epic technical figure, OmniGraffle and OmniGraffle Pro keep it gorgeously understandable.