The inspiration behind this app was to solve a very simple problem that I a lot of people experience. Namely, keeping check on how much annual leave they've used up so far in a given year.
We built this app over a couple of days to answer this question – and only this question.
Using HTML5 technologies, the app is 'installable' on a mobile phone by simply adding it to your home screen. All the date you enter is simple stored locally on your own device. It even works offline.
Initially made for sale at a bargain price of £1, we've since open-sourced the code and made it available to anyone, free.