Seider studied singing at the Musikhochschule in Köln.
He made his debut in 1926 at the Bühnen-Volksverein Köln in Il matrimonio segreto.
During 1928-30, Seider sang at the Stadttheater on Halle (Saale). After, Seider was first Heldentenor until 1945 at the Opera in Leipzig.
Seider made Guest appearances:
1933, Teatro Colón (Walther von Stolzing, italienischen Sänger).
1937, Münchner Opernfestspielen.
Seider appeared several times at the Festspielen in der Waldoper von Zoppot.
1935 and 1938: Wiener Staatsoper: Max (December 17, 1938), Lohengrin (May 18, 1935 for a total of 3), Walther (January 3, 1938), Manrico (
May 22, 1935 for a total of 2).
1937. Berliner Staatsoper.
1938, Festspielen in Salzburg (Walther von Stolzing).
1939, Maggio musicale Firenze (Erik).
1940 and 1943: Teatro Liceo.
1941, Stadttheater in Zürich.
Since 1936, Seider appeared several times at the Staatsoper von Dresden.
After the war, Seider moved to Munich where was a member of the National Theater during 1947-67.
In 1947, Seider sang Tristan at Covent Garden. In 1950, he sang the same role at the Rome Opera with Maria Callas (February 6/9/19/25/28, with
Elena Nicolai, Benvenuto Franci, Giulio Neri, Virgilio Stocco, Gino Conti, Mino Russo, Paolo Caroli, Tullio Serafin).
He toured South Africa in 2952. He went to Covent Garden in 1953 to sing in the English premiere of Die Liebe der Danaë.
Seider also sang at the Teatro San Carlos in Lisbon (1949, 1954), the Teatro Massimo Palermo (1954), at the Opera in Rio de Janeiro (1957)
and at the Opéra in Paris (1963, Wozzeck with Elga Pilaczyk, Heiner Horn, Kieth Engen, Beissner, Louis Devos, Pierre
Boulez on november 29, decmber 2, 6, 8, 14, 16, 22, 29, 30).
He retired in Gräfelfing near München.
He recorded for Odeon, Polydor (since 1933), several operas for Urania (Tannhäuser, Walküre).
Reference: Kutsch & Riemens