She is perhaps best known for her series of charming children's books about Mimff, all of which were illustrated by Edward Ardizzone.
Kaeser had a birth defect that impaired her walking, and as a child became an avid reader.
Educated in Berlin, she worked at a publishing company after leaving school, and in 1925 became editor of a children's magazine.
On Hitler's access to power in 1933, she and her husband left Germany, first for France, then to Denmark in 1934, and finally in 1935 to Sweden.
Kaeser's other works include: A Jewish feminist, Kaeser also wrote biographies, primarily of significant women in history, including: Many of her books were published in Swedish, Danish, Finnish and Norwegian (as well as German and English).