I would like to store data using google protocol buffers (another serialized format would work, too), and then have an UI to browse that data. Is there a C++ framework/API that
If you want to write it yourself, one option could be to use Python/PySide together with QML, process your data and store it in a QAbstractListModel which is connected to your QML ListView. Depending on the complexity of your data, the list view delegate should hopefully be able to visualize it.
This question might be useful in that case: How to provide data from PySide QAbstractItemModel subclass to QML ListView?
If XML is an option, the QML XmlListModel is very neat and easy to use.