Given John von Neumann's heavy involvement in war-related projects, it is plausible that Klára was involved in the war effort in some capacity. However, there are no definite records of her official employment, nor details of what this work could have consisted of.

Began working directly with computers, particularly the ENIAC and later the MANIAC at Los Alamos National Laboratory. She became highly skilled in programming these early machines, a field that was just emerging. Her logical thinking and aptitude for problem-solving were crucial in this role.

Collaborated with John von Neumann and other scientists at Los Alamos on various computational problems. She played a crucial role in translating mathematical problems into code that could be executed by the computers. This collaboration showcased her ability to work in a highly technical and demanding environment.

Contributed to the development of early programming techniques and methodologies. Her experience with ENIAC and MANIAC helped her understand the complexities of computer programming and develop efficient coding strategies. Her knowledge of the computer's intricacies significantly helped in optimizing code for performance.

After John von Neumann's death in 1957, Klára continued to work at Los Alamos, solidifying her position as a respected and experienced computer scientist. Her independence and continued dedication show her resilience and commitment to her work.