Klart in Swedish means "clear", "finished/done" or "of course" depending on what context it is used in.

E.g: Klart jag ska = Of course I will

Considering this application is built by Swedish developers, I'm guessing its name originates from the Swedish language.

I wonder if that's from colonial usage, 'clart' is a Northern English/Scottish term for muck, attested since at least 1808: https://books.google.co.uk/books?id=UGAJAAAAQAAJ&printsec=fr...

it's most commonly used as 'clarty' now here: http://www.scotsman.com/news/scottish-word-of-the-week-clart...

Jamieson's etymological dictionary suggests south germanic 'Kladd' as the origin of the Scots term.

LPT: Never click on an Urban Dictionary link if you're at work.