Seider studied singing at the academy of music in Cologne.
He made his debut in 1926 at the Bühnen-Volksverein Köln in Il matrimonio segreto.
1928–30, Seider sang at the Stadttheater in Halle an der Saale. After that and until 1945, Seider was first heldentenor
at the Leipzig opera.
1933 Teatro Colón (Walther von Stolzing, Italienischer Sänger)
1937 Münchner Opernfestspiele
1935 and 1938 Vienna Staatsoper: Max (17 December 1938), Lohengrin (18 May 1935, total 3), Stolzing (3 January 1938), Manrico
(22 May 1935, total 2)
1937 Berlin Staatsoper
1938 Salzburg Festival (Stolzing)
1939 Maggio musicale fiorentino (Erik)
1940 and 1943 Teatre del Liceu
1941 Stadttheater Zürich
Seider appeared several times at the Zoppot open air festival, as well as, from 1936, Seider at the Dresden Staatsoper.
After the war, Seider moved to Munich, where was a he member of the Staatsoper from 1947 to 1967.
In 1947, Seider sang Tristan at Covent Garden. In 1950, he sang the same role at the Rome Opera with Maria Callas (6/9/19/25/28
February, with Elena Nicolai, Benvenuto Franci, Giulio Neri, Virgilio Stocco, Gino Conti, Mino Russo, Paolo Caroli, Tullio
He toured South Africa in 1952. He went to Covent Garden again in 1953 to sing in the English premiere of Die Liebe der Danae.
Seider also sang at the Teatro São Carlos in Lisbon (1949, 1954), the Teatro Massimo Palermo (1954), in Rio de Janeiro
(1957) and at the Opéra in Paris (1963, Wozzeck with Helga Pilarczyk, Heiner Horn, Kieth Engen, Beissner, Louis Devos, Pierre
Boulez on 29 November-2/6/8/14/16/22/29/30 December).
He retired to Gräfelfing near München.
He recorded for Odeon, Polydor, and complete operas for Urania (Tannhäuser, Walküre).
Reference: Kutsch & Riemens