Zotero is an open source plugin for Firefox for managing research papers collections. You can use online zotero storage (pretty small) or use third-party sync application. I use Yandex Disk for this purpose: 10 Gb it quite enough for a moderate research library. zotero can automatically fetch article metadata (author, year, etc) from the web (like Mendeley and similar software do).
Posts with the tag zotfile: