[1] A product of Basque Country giants Real Sociedad's youth system, López was born in Irun, and made his first appearances with the first team in the closing stages of the 1992–93 season, having played understudy to the inconsistent Javier Yubero for most of the year.

He would be the undisputed starter from the following campaign onwards, missing only a total of seven La Liga games in the next seven years (in 1997–98, as Real ranked third, he played all 38 matches and conceded 37 goals).

In 2006–07, he helped the side to return to the top flight after a three-year absence[3] while also collecting a Ricardo Zamora Trophy – 36 matches, 29 goals.

[4] In the following season, López acted as backup and helped develop wonderkid Sergio Asenjo (20 years his junior),[5] and had his contract extended until June 2009 after which he retired at the age of 40.

[6] He joined Juan Carlos Mandiá's staff at Deportivo Alavés two years later, being named his successor late into the second-tier campaign[7] and eventually leading the team to safety.