Dia is an online diagram editor, graphs and charts creator.
It supports UML diagrams, entity-relationship diagrams, network diagrams and more. Dia is roughly inspired by the Microsoft Visio, though more geared towards informal diagrams for casual use. This tool can be used to draw many different kinds of diagrams and create charts.
As a diagram maker has special objects to help draw entity relationship diagrams, UML diagrams, flowcharts, network diagrams, and many other diagrams. It is also possible to add support for new shapes into Dia diagram editor by writing simple XML files, using a subset of SVG to draw the shape. It can load and save diagrams to a custom XML format (gzipped by default, to save space), can export diagrams to a number of formats, including EPS, SVG, XFIG, WMF and PNG, and can print diagrams (including ones that span multiple pages).
Try Dia on rollApp for free with no download and save your docs on Dropbox, Google Drive, and other cloud storages.
Most features run, but the only issue I am having is opening and saving files on the Cloud is extremely slow. The issue may not be with Dia at all. I was able to load up a file I had created with Dia on Linux and it looks identical with all of the familiar settings available when comparing features of the desktop versus the rollApp version.