Born in the United States, he represented El Salvador national team at international level, appearing for them at the CONCACAF Gold Cup in 2011 and 2013.

Purdy was waived by Dallas on September 11, 2009, in a move that freed up the cap space for them to sign Heath Pearce.

On January 26, 2011, Purdy was signed by Portland Timbers to compete in the club's first season in Major League Soccer.

[11] Rubén Israel, new head coach of El Salvador, selected Purdy for the 2011 CONCACAF Gold Cup tournament,[12] and he received his first cap when starting for the squad in the quarterfinal match against Panama.

[13] Purdy scored his first goal as well as had his first assist for El Salvador in a match against the Cayman Islands at Estadio Cuscatlán on October 11, 2011.