Sharepoint's lists functionality is powerful. Because I don't want all the other functionality of Sharepoint, I have been looking for an alternative (preferrable open source) without much success.

Basically I want to have a platform or web application that:

1. allows us to define custom datatypes (for different kinds of customer products)
2. has the possibility to create views or forms to present to the user for reading, creating or updating the information of the items of a given datatype
3. a ui to setup this configuration is not required but would be nice to have

In an ideal scenario there is an API to get the data out afterwards for further processing.