This product is NOT free. Only the crippled trial version is free. To unlock all the features and get full functionality the author wants $15. Given the the formula for board-foot is so simple, the price of this product, and the cost, of AppleWorks, if you already do not have it, my advice is to buy AppleWorks instead and enter the formula into its spreadsheet. Then you have a program in which to calculate your board-feet, list a bill of materials and draw up your design as well as do a whole lot of other things. AppleWorks cost $79 from Apple, a difference of only $65, but you also get a word process, drawing program, painting program, spreadsheet, and database - all the computer tools you need to complete you entire woodworking project and and that you can use for a lot of other things.
It is not that this won't work but as a woodworker myself (ShopSmith owner) it just seems like a lot of money to spend to complete a package so that you can print, and export your results, when all the product basically does is the following formula ( in inches):
(Length x Width x Thickness)/144
To be fair I should state that I am basing this comment on the authors website description and screen shots. I have not downloaded the product, but I did create a spreadsheet in less than 10 minutes that did the same thing, minus the fraction to decimal conversion. I could do that but it would take a little longer.