This app distinguishes itself in it’s ease of use by instantly calculating rates without having to press extraneous buttons. When negotiating a loan, this can be useful on both sides of the table by allowing the users to convert from APR to Effective rate and back seamlessly and effortlessly.

What The EFF is a simple JavaScript & HTML5 powered converter. This is not the first APR/EFF converter, but it’s definitely the most intuitive. The app makes use of HTML5 caching (you can use it offline), Jasmine testing suite and Shifty. I developed this app specifically for Webkit browser; Chrome & Safari.

Check it out here.