Drawing block diagram?

Question

Is there any software that allows to draw block diagrams like this:

• http://upload.wikimedia.org/wikipedia/commons/f/f5/Windows_2000_architecture.png

Or like this:

• 

Answer 1

For mac / iOS

Omnigraffle is popular for that sort of thing, if what you want is to make connected-block arrow-heavy flow diagrams quickly.

I don't use it myself, but I know a few information designers who swear by it as a simple way to put together an outline for a diagram, organise their thoughts and get the layout, content and structure right. They then export to Adobe Illustrator to design the presentation of the final product - you could skip this final step if you're just making simple diagrams like that.

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For PC

I've heard vague but positive things about Visio, and people sometimes describe Omnigraffle as 'Visio for Mac' so I think they're fairly equivalent.

You can also browse software alternative lists like this one.

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Online/for everything else

You can also play around with the browser based yFiles. Their website is a bit confusing, here's a free live example.

Answer 2

My favourite software for this is actually a web-based editor, Cacoo.

It's very good at most linked diagram styles (both your examples are quite easy to make with Cacoo), and is much more user-friendly than Visio (though not as in-depth). It's also cross-platform due to it being web-based, and seems to have an offline mode, though I don't use that personally.

The reason I settled on Cacoo was actually because of its collaboration feature, that allows multiple users to be working on the same diagram at once. Obviously this doesn't work so well in offline mode, but is surprisingly effective when you want to show someone an idea or make quick changes.

I pair Cacoo with MindMeister for mind-mapping, and have all my diagramming needs covered.