UMLetino is a free online UML tool for fast UML diagrams. It runs in your browser, and does not require any installs.
It is based on UMLet (which is available as stand-alone tool or Eclipse plugin), and shares its fast, text-based way of drawing UML sketches.
Main features: install-free web app; save diagrams in browser storage; support for many UML diagram types; simple, markup-based UML element modifications; png export.

New in current version 13.3: new command transparency= to set transparency, several bugfixes

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