KATZ-FM (100.3 MHz, "The Beat") is a commercial radio station licensed to Bridgeton, Missouri, and serving Greater St. Louis.

It airs two nationally syndicated shows on weekdays: The Breakfast Club in morning drive time and Way Up with Angela Yee in middays.

Its HD2 digital subchannel carries the Black Information Network, an all-news radio service from iHeart which feeds FM translator W279AQ at 103.7 MHz.

But under its original owners, it was never successful and was always behind KMJM in terms of ratings and audience, which dates back to their days as rival disco outlets in the late 1970s.

For a while, it had performed successfully under Clear Channel ownership and had proven to be a good complement to Rhythmic-leaning Top 40 sister KSLZ.

But KATZ was chosen because Clear Channel did not see it fit to replace Tony Scott, who was doing morning drive at KMJM.

Finally, at 12:01 a.m. on December 26, 2009, "100.3 The Sound" debuted with a Modern Adult Contemporary/Modern Rock hybrid format and new call letters WSDD.

On November 7, 2012, at 9 a.m., just five months after The Brew's debut, KBWX ended the classic rock format, and became the new home of KMJM's urban adult contemporary format, and rebranded as "Majic 100.3" (their former frequency, 104.9 FM, flipped to Rhythmic CHR and took the KBWX calls, while 100.3 received the KMJM-FM call letters a few days later on November 15).

On November 18, 2014, at Noon, the station returned to the "100.3 The Beat" moniker, and flipped to a Classic hip hop format.