you can design them by hand, as long as they have similar Tm, then use "primer blast" to check for specificity! There is trial and error but most likely it will work fine for you..

all you need is to change the 3' of one primer to fit different SNPs. The reverse primer can be chosen by primer blast according to the size range. But try to avoid regions of multiple adjacent SNPs.

www.ncbi.nlm.nih.gov/tools/primer-blast/

Thanks Yazan Haddad , Do you recommend other software for primer design 

I have used primer3 successfully for a long time but then again you should use blast to check for specificity. Since you are interested in genotyping the main challenge is to avoid identical sequences that come from pseudogenes on distant chromosomes.. again blast is a good method to detect them. One example is the kras gene where many reported SNPs and mutations are false and rather belong to similar sequence of a pseudogene.

http://bioinfo.ut.ee/primer3/