Koop is the Swedish electronic jazz duo of Magnus Zingmark and Oscar Simonsson. Though the music may sound as if it is played by a tight jazz group, it is actually sample-based. Thousands of small clips of drums, strings, horns, and choirs are taken from old records and puzzled together into new songs. This time consuming production process is one of the reasons Koop's albums are released 4-5 years apart.

The group's 3 albums all feature guest vocalists. On their latest, "Koop Islands", the singers are Yukimi Nagano, Ane Brun, Hilde Louise Asbjornsen, Rob Gallagher and Mikael Sundin. Also contributing to the percussion, solos, and bass are Mattias Ståhl, Magnus Lindgren, Karl Frid, Nils Berg, Martin Höper, Ola Bothzén, Dan Berglund and Mats Lindfors.

Live, Koop transforms into a 7-9 piece swing orchestra including 1-3 singers. The lineup varies from time to time.

Koop prefers to label their music "romantic swingtronica".