Also chiming in to say I used Zotero for my Master's thesis and I was happy with it. With some plugins (I don't remember exactly) I had a very nice pipeline of "find paper on the interntet" -> Zotero -> automatically updated .bib -> trigger rebuild of Latex document to PDF -> automatic reload in PDF viewer. The UI is somewhat dated but the functionality is great. Nowadays I would probably choose Citationsy, maybe onl…
> We don’t have to promise to keep your data safe — because we don’t collect it in the first place... Citationsy lives in the cloud and is accessible from anywhere... Your data is saved in the cloud and backed up every 10 minutes
> Nothing to install, update, or patch... Use our iPhone and Android apps to cite books on the go with our barcode scanner and add the Chrome or Firefox extensions to cite websites in 2 clicks.
Perhaps I missed the use case where you retain your data, or there's a version you can self host?