Feder was born in Würzburg, Germany on January 27 1883 as the son of civil servant Hans Feder and Mathilde Feder (née Luz). After attending humanistic schools in Ansbach and Munich, he studied engineering in Berlin and Zürich (Switzerland); after graduating, he founded a construction company in 1908 that subsequently was particular active in Bulgaria where it built a number of official buildings.
From 1917 on, Feder studied financial politics and economics on his own; he developed a hostility towards wealthy bankers during World War I and wrote a "manifesto on breaking the shackles of interest" ("Brechung der Zinsknechtschaft") in 1919. This was soon followed by the founding of a "task force" dedicated to those goals that demanded a nationalisation of all banks and an abolishment of interest.
In the same year, Feder, together with Anton Drexler, Dietrich Eckart and Karl Harrer, was also involved in the founding of the Deutsche Arbeiterpartei ("German worker's party", DAP), which would quickly change its name to Nationalsozialistische Deutsche Arbeiterpartei (NSDAP). In February 1920, together with Adolf Hitler and Anton Drexler, Feder - who also was a member of the Thule Society - drafted the so-called "25 points" which summed up the party's views, and also introduced his own anti-capitalist views into the programme. When the paper was announced on February 24 1920, more than 2000 people attended the rally.
Feder took part in the party's Beer Hall Putsch in 1923; after Hitler's arrest, he remained one of the leaders of the party and was elected to the Reichstag in 1924, in which he stayed until 1936 and where he demanded freezing of interest rates and dispossession of jewish citizens. He remained one of the leaders of the anti-capitalistic wing of the NSDAP, and published several papers, including "National and social bases of the German state" (1920), "Das Programm der NSDAP und seine weltanschaulichen Grundlagen" ("The programme of the NSDAP and the world views it's based on", 1927) and "Was will Adolf Hitler?" ("What does Adolf Hitler want?", 1931).
Feder briefly dominated the NSDAP's official views on financial politics, but after he became chairman of the party's economic counsil in 1931, his anti-capitalist views led to a great decline in financial support from Germany's major industrialists. Following pressure from Walther Funk, Albert Voegler, Gustav Krupp, Friedrich Flick, Fritz Thyssen, Hjalmar Schacht and Emile Kirdorf, Hitler decided to move the party away from Feder's economic views; when he became Reichskanzler in 1933, he appointed Feder as under-secretary at the ministry of economics in July, disappointing Feder who had hoped for a much higher position.
Feder continued to write papers, putting out "Kampf gegen die Hochfinanz" ("The Fight against high finance", 1933) and the anti-semitic "Die Juden" ("The jews", 1933); in 1934, he became Reichskommissar (Reich commissioner) for settlement.
After the Night of the Long Knives, where officials like Gregor Strasser and Ernst Röhm were murdered, Feder began to withdraw from the government, finally becoming a professor at the Technische Hochschule in Berlin in December 1936, where he stayed until his death in Murnau on September 24 1941.