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Sorry, that was I. G. Farben, also still extant. It was intended as a pesticide; used properly (as seen below, in a specially-made sealed container), it was a minimal hazard to humans.

It had been developed by Deutsche Gesellschaft für Schädlingsbekämpfung mbH (Degesch), a state-controlled consortium formed in 1919 to investigate military use of the chemical. Degesch was taken over by the Deutsche Gold- und Silber-Scheideanstalt (German Gold and Silver Refinery, Degussa) in 1922.

I. G. Farben obtained a 42.5% share of Degussa in 1930 and continued to market the product through that brand.

Prior to World War II Degesch (owned by Degussa, in turn majority-owned by I. G. Farben) derived most of its Zyklon B profits from overseas sales, particularly in the United States, where it was produced under license by Roessler & Hasslacher prior to 1931 and by American Cyanamid from 1931 to 1943. From 1929, the United States Public Health Service used Zyklon B to fumigate freight trains and clothes of Mexican immigrants entering the United States. Uses in Germany included delousing clothing (often using a portable sealed chamber invented by Degesch in the 1930s) and fumigating ships, warehouses, and trains. By 1943, sales of Zyklon B accounted for 65 percent of Degesch's sales revenue and 70 percent of its gross profits.

Degesch resumed production of Zyklon B after the war. The product was sold as Cyanosil in Germany and Zyklon in other countries. It was still produced as of 2008. Degussa sold Degesch to Detia-Freyberg GmbH in 1986. The company is now called Detia-Degesch. Up until around 2015, a fumigation product similar to Zyklon B was in production by Lučební závody Draslovka of the Czech Republic, under the trade name Uragan D2. Uragan means "hurricane" or "cyclone" in Czech.

Most of the above from Wikipedia, which includes footnoted sources.