The station went on the air as KJIM on June 15, 1987, with power of 5 kilowatts during daytime hours and reduced power of 1 kilowatt nighttime. On January 2, 1990, the station changed its call sign to KRZN, and on December 13, 1993 to KTLK. On January 7, 2002, the station's call sign was changed to KKZN. The station initially began broadcasting with an all-Christian all-talk format. It was owned by Sudbrink Broadcasting. The station hosted satellite radio and Christian news/talk. The station also played Contemporary Christian Music with a Top 40/Album Oriented Rock hybrid style. Though the studio was new and built out for talk, very little took place there. In November 1987, of Boulder started broadcasting Addiction Free Radio on weekends. In the Spring of 1988, Scott became English talk program director. Scott launched Jann Scott Live, Race Day Radio Magazine and gave people such as Claudia Lamb and Bill Hammel their start in radio. The station programmed Mexican music in the Mornings and evenings up until 1990. Jann Scott is one of the few hosts on the station to win 2 Westword's Best Talk show Host awards: 1988 for Addiction Free Radio and 1989 for Race Day Radio Magazine. He also won Rocky Mountain News Top 10 Ten Colorado Broadcaster award. In the 1990s, the station moved to Music and then, in 2002, to all-sports as "760 The Zone," from which the KKZN call sign is derived. After that, the station switched to progressive talk as the Denver affiliate of the Air America radio network in August 2004.
During its previous progressive talk format, the most popular local talk host on KKZN was David Sirota, also a newspaper columnist. In March 2009, Sirota took over the morning time slot of The Jay Marvin Show, hosted by local talk show host Jay Marvin, when Marvin was forced off the air due to ill health. Sirota moved to Clear Channel Communications sister station KHOW in 2012, co-hosting an afternoon show with Michael Brown until Sirota's departure in January 2013. Besides broadcasting progressive talk shows, KKZN also ran what it called a . This list included companies that supported progressive causes and interests. The station also sponsored progressive events throughout the Colorado Front Range, such as events for the ACLU and other progressive organizations. On January 21, 2010, Air America filed for Chapter 7 Bankruptcy, and ceased live programming the same night. Reruns of Air America's programming continued to air until Monday January 25, 2010 at 7 pm Mountain Time.
On May 7, 2014, Denver Post television critic Joan Ostrow reported that Gloria Neal, who anchors the 6 pm newscast on KCNC-TV along with hosting KKZN's morning show, had been released from her contract, and mentioned on Facebook that the entire staff had been let go, suggesting an oncoming format change. On May 19, 2014, KKZN shifted their format to lifestyle/advice talk, branded as "Real Talk 760" with all syndicated personalities, including Dave Ramsey, Jim Bohannon, Clark Howard, Dr. Joy Browne, and Tom Martino, along with a late night radio replay of TMZ Live. Weekends, besides Leo Laporte's The Tech Guy, consisted of brokered programming.
On June 25, 2019, KDSP changed its call letters to KDFD. On July 8, 2019, KDFD began stunting with songs themed on patriotism or containing the word "Freedom", interspersed with promos stating that "Freedom" was "coming soon". It also began simulcasting on the FM translator 93.7 K229BS in Lakewood, Colorado. On July 15, 2019, the station launched a new conservative talk format branded as Freedom 93.7. The station's lineup consists entirely of syndicated personalities; Glenn Beck and Sean Hannity were being moved from sister station KHOW, and Rush Limbaugh was being moved from KOA. As a transition period, KHOW and KOA continued to air these three programs, but they would eventually be replaced by local programming and air exclusively on KDFD in the future. It was reported that iHeartMedia's hiring of former Broncos player and KKFN host Alfred Williams to host a new show on KOA was a main impetus for the flip.
