There are many Internet sites that offer a free coat of arms based a family's surname. However, there is no such thing as a family coat of arms because coats of arms were awarded to individuals, not families, according to About.com.
Coats of arms generated for free or purchased on the Internet based on a surname may have no actual relation to the person's family. To a person to find a genuine coat of arms for his family, he must find out if he has an ancestor that was awarded a coat of arms from an official source. To do this he must research his family tree. If he finds a relative who was issued a coat of arms, he can contact the College of Arms of the country that issued it, and request a records search.
Coats of arms originated as ways to identify knights in the 1100s. King Henry I of England gave his son-in-law a blue shield with four golden lions in 1127. This is the first recorded example of a coat of arms on a battle shield. By the 1400s, a knight had to have a coat of arms to be allowed to participate in tournaments, and the coat of arms became a symbol of noble status.