You can get Melanto Calculator as Chrome App or extension. To install it -- just go to chrome web store and search for "Melanto Calculator". Click "Install" and the calculator app will be available for offline use (available as standalone app and chrome extension)
Google Chrome
Opera
The app is also available as Opera Next extension (Opera 15 and newer). To get the calculator for Opera - just go to the Extensions library, select "tools" and search for "Melanto Calculator". Or open the current page in Opera and click the link below.