I have used Beer-Smith and Brew-target, both worked very well and are well worth the money. Although Brew-target is free you should provide some recompense to the coder it is good software. Like I said I used both for a trial/test, although both are very good I went back to what I have developed on my own.
I have a spreadsheet that calculates out target OG and FG based on the malts used and the malt analysis sheets, and the yeast characteristics. Also calculates the IBU based on hop AA% also calculates the amount and temperature of strike water and the amount of sparge water. Adding the calculations for adjustments to my brewing water based on my water analysis report from Wards. Just now getting into those math equations and adding them to EXCEL.
Once I get the spreadsheet fine tuned going to build an access database to stare and report on my recipes. Of course this is just for my use and is highly personalized to what I want.
But if you like Beer-Smith buy it. You can try out Brew-Target and if you like it donate to the coder. Developing stuff like that is a lot of work, effort and thought. Plus the testing and updating and maintaining to run at current software levels is a lot of work. So pay the guy who does the work.
Good Luck