We’ve covered some free alternatives to Visio before, such as the online Gliffy and this cross-platform app, but Diagramly is one of the better no-hassle options available. As soon as you visit Diagramly you can instantly start creating a diagram without having to mess around with registering for an account or downloading software. It’s about as good as it gets in terms of a free diagram maker.
The interface is very intuitive so it won’t take much for you to get going, but the pre-designed objects leave a little to be desired. Programs like Visio have a vast library of objects to choose from, and at this point Diagramly is rather meek in that area. Assuming they have the objects/libraries you need then this is a pretty sweet alternative.
You may be wondering how you are able to save your work if you don’t have to register for an account? Well, clicking on the Save button will trigger the download of an XML file to your machine where all of the configuration data is stored. You can then upload that XML file at any point to make changes to it. It’s not quite as hassle-free as saving it online, but at the same time you don’t have to worry about a storage limit. Oh yeah, and you can also upload and open Visio VDX files.