This site offers 122 birthday cards you can download and print. Choose cards with animals or balloons, flowers, or cards with cake. There are designs for adults and ones for kids.
Cards are available in two sizes: a larger size card that you fold in half (measures 8.5 inches tall by 5.5 inches wide,) and a smaller size that is folded in quarters (to make a 4.25 inch by 5.5 inch card.) Each printable birthday card is available for free as a PDF, or you can choose editable versions (in DOC format) for just $3 each.
Every birthday card here is unique to this site. Enjoy.