Web Applications

common web applications could be big, like search engines. this is a list of open-sourced self hosted services:

https://github.com/awesome-selfhosted/awesome-selfhosted

cat as a service not infinite user provided content:

https://cataas.com/#/

https://cataas.com/cat/gif/says/Hello?filter=sepia&color=orange&size=40&type=or