Karoly started producing music in the 90's, joined by Monica for vocals in 1998, forming the duo Karoly & Monica.

They rose quickly in popularity and became one of the most successful artists on MP3.com around year 2000, topping not only their sub-genre EDM charts, but also the parent charts all the way up to the worldwide global chart at #1 place for weeks. During those years their music was streamed in the millions around the globe and there are countless fan stories of how their music introduced the listeners to EDM and trance.

In 2004, they paused music productions and their last released track was a remix produced for Swedish grammy nominee 'Richi M' in 2004.

In 2021, Karoly took up music production again under their alias Karoly & Monica, with the first two releases set to Dec. 2023.