The more I dwelve into the world of quick development (be it a Metasploit plugin or a proof of concept website) the more I feel the need to be able to quickly sketch what's in my mind.
Ok, this might have something to do with the fact that I try to delegate coding, but still, I'm always positive that shipping is a feature. Accordingly, being able to ship a design and sketch idea is better than nothing. Maybe there will be a social network one day for aborted design and ideas...
In the meantime, I've explored online solutions which lets you build a sketch (or mockup, or wireframe). I've been focusing on tools to build web sites/web applications, not binary interfaces, able to work with Chrome under Linux (or Firefox, if needed). And no lenghty registrations or lame trials.
So, here is my personal top 10 (9, ok) of mockup software
Lumzy is 100% free, and it only took me 10 seconds to sign up and be able to save projects. It can export in various format, it is easy to share projects, has a big library of ready-made objects and does even support a basic scripting language which can make the mockup browsable and actionable!
IPlotz takes a more integrated approach, providing very basic project management features which "real" designers will love. Anyway, even in its free mode where you only have one project it is as good as Lumzy
balsamiq.com, an Italian (!) startup provides very professional-looking mockups: unfortunately, they focus on the desktop version of their application. The web based editor would be superior to anything else, but it is apparent it is a demo and lacks feature such as saving or sharing.
Pencil project is a bit out of scope here: it requires a Firefox addon to be used in the browser: as such it is similar to a desktop application in the fact that it runs completely on the local machine. However, since it is embedded in the browser once it has been installed, I'm considering it here. Overall, the user experience is inferior when compared to the other solutions, even though I do appreciate the presence of various types of the same control: from a prototyping app I expect a lot of readymade components, otherwise I will just go for a standard "paintlike" software.
I appreciated Mockingbird for its great library of icons and web-oriented stuff. However, it will be non-free starting form the 1st of September, and that puts it off our competition.
In my opinion MockFlow doesn't really add anything from a tool perspective. However, it is still worth mentioning thanks to its wonderful store! Great idea.
ForeUI also only has a demo online, and in Java too. Doesn't meet the requirements, just like Inpreso which nags you with a billion popups even while you're testing it.
Fluidia looks promising but it's still in early alpha.
So, what did I like the most? In the end, I went for iPlotz: the rest are presented in my personal ranking.
PS: obviously, for the color palette I went for Kuler !