I checked out the profile by their main software architect Guido Steinacker [1], their job offerings on otto.de [2], their github (they have repos for classic Java EE patterns, like their Wicket component tester and HAL stuff, which is a default in spring data) [3], and their stepstone, which mostly shows spring and java jobs [4]. There is no single asp.net job listed and they also don’t have anything asp.net related on their github. I don’t think that builtwith is an accurate data source.

[1] https://www.xing.com/profile/Guido_Steinacker

[2] https://www.otto.de/jobs/de/jobsuche/-java/index.php

[3] https://github.com/orgs/otto-de/repositories

[4] https://www.stepstone.de/cmp/de/Otto-GmbH-Co-KG-28607/jobs.h...