Wersi began manufacturing do-it-yourself electronic organ kits in 1969. Wersi designed its organs to be upgradable through software and hardware, so each organ model would not become obsolete as quickly as competing manufactures' models. From 1969 and 1977, Wersi produced the "W" analogue, "DX" digital, and "CD" digital series organs. In 1991, Wersi ended production of organ kits, and introduced mew models of complete organs: the Pegasus, Performer, Penta, Phon-X, and Rhondo classic. In 1997, Wersi was taken over by Thomas Music, and many models were renamed. In 2002, Wersi released the current OAS series.

1969 gründen die Gebrüder Wilhelm-Erich Franz und Reinhard Franz die Firma WERSI. Der Name WERSI ist abgeleitet von dem Geburtsort WERlau und der seinerzeitigen Kreisstadt SImmern.