No contact for the developer in the app or on the website, so comments posted here. Even ran WHOIS on 'contrasteapp.com' and found the contact info is hidden by WhoisGuard (in Panama). Developer really doesn't want to be contacted.
Clicking on a web safe color in the Apple color picker to select a color for either the text or background changes the color to something other than what is picked. For example CCCCCC becomes D6D6D6. This is the case whether one uses the select button or the eye dropper tool.
There needs to be some sort of indication of which color area is active--the one currently being picked. It's too easy to confuse them and inadvertently replace, say, the foreground when one means to replace the background.
A great start for a handy little app that addresses one of my pet peeves about many website designs. If this gets designers to think more about accessibility it will be a great help.