I don’t make diagrams every week, but once in a while I will have to create a flowchart, an entity-relationship diagram, a site map, an org chart, or such. For diagrams with boxes and connectors, working in a standard vector illustration app, like Illustrator or Affinity Designer, is cumbersome, as you have to manually re-arrange all the connectors if you move your boxes around. So for many years I have turned to Omnigraffle–a program purpose-built for diagramming. Unfortunately, my version of Omnigraffle no longer works on my current operating system, so I had to look for a new tool. What I found was an array of desktop and online apps, most of which required either online registration and a monthly fee, or a hefty up-front payment. And then I found draw.io, which requires no registration at all, it works in any browser or in an offline app on most operating systems, you can easily integrate into Google Drive to collaborate on diagrams, and which is completely free.
I honestly don’t know how any of the premium diagramming apps are still in business, as draw.io can do just about everything they can do, and is just as easy to use. Finding it was like discovering a wormhole back to earlier days of the Web, when lots of people made things you could use for free, just because it was cool. They don’t collect your data–you don’t have to enter so much as an email address to use it; they don’t hide valuable functions behind a “pro” tier; they don’t make you look at a single ad. It’s all free and open-source.
And the other apps are not cheap, especially if you have to create a diagram only occasionally. My old favorite Omnigraffle will set you back at least $100. Gliffy, SmartDraw, Lucidchart and Visio have online-only services that will cost you $5-$10 a month. I admit that I am not a frequent diagram-maker, so maybe there are benefits that these apps have that draw.io does not. But draw.io did exactly what I needed it to do, and had lots of handy features.
Do you want to work online? Just go to draw.io and start diagramming. You can import diagrams created by other apps, such as Visio or Lucidchart. You can save your diagram on your hard drive, or in Google Drive or OneDrive. You can export your diagram in many formats, including as a URL, or an embed-able HTML snippet–all without saving the diagram on the server, which means your data is entirely your own. There are lots of templates to get you started, and an extensive library of shapes. (Click the ‘+ More Shapes’ link at the bottom left to choose which shape sets you want to see.)
Draw.io online works in any browser, but if you want to work offline, there’s a downloadable app for Windows, macOS, several flavors of Linux, or Chrome OS. If you use Google Drive, you can install a draw.io app via the G Suite Marketplace, and an add-on to integrate draw.io with Google Docs.
The only drawback that I can see is that you can’t easily collaborate on a diagram with others unless you’re using Google Drive and the G Suite app. If you’re outside of Google Drive, you could save your diagram on a shared Dropbox or OneDrive location, and so multiple people could access it, but it would not be the same as working on the diagram together at the same time. That seems like a minor inconvenience, though, especially considering how easy-to-use and flexible draw.io is otherwise.