title_body: How to manage my e-book library across my devices So I have a reasonable collection of ebooks, and it starts to be a mess.
  My collection is a mixture of ebooks from Amazon (Kindle) and pdf.
  
  I have one laptop, one kindle, one android tablet and one main PC.
  
  For the reader part, I'm fine with what I have: kindle for novel, adobe pdf reader for windows PC and laptop and a good reader for the tablet.
  
  What I miss is a way to centralize and share metadata around those books:
  what I have read, not read, what's next, short comments, rating, ...
  
  Right now I'm using Calibre on the laptop, because it was my main device.
  The drive is synced to my onedrive account, so I can access my books from every browsers and thank to portable Calibre install, I can even run calibre from any windows machine.
  
  So basically I have many book management systems (Kindle, Calibre) that are synced by cloud, but this is not good for my tablet: Kindle and onedrive are storing the file in internal memory (short) while I have a big sd card.
  I also have no way to share my metadata with the table which starts to become my main reading device for pdf.
  
  I would like to have a central library for metadata that I can update from many places, and a way to replicate my ebooks in all my devices, in my favorite location (sd card for Android) so I can read what I want without an internet connection. In addition this central library should be able to integrate with my kindle books and other library system.
  
  Do you know if such a centralized software exists ?
  If no, what would be the closest thing to my need ?
upvoted_answer: Ok, so here is my current solution, which is not perfect but that corresponds more or less with my current need.
  
  
  PC with windows are using the portable version of Calibre. The library and the metadata are stored in a specific dir in  my filesystem that is synchronized with my local onedrive directory.
  Android devices are using the Calibre Companion app ($4) and are configured to use my onedrive cloud account.
  I'll probably change that in order to use a cloud synchroniser tool to mirror my cloud storage to the SDCard and point Calibre Companion to my local storage instead !
  IOs: don't need it at the moment.
  
  
  What needs to be improved:
  
  
  possible conflict between metadata of pc version: I need to investigate if I can have a centralized version of calibre that can received updates from secondary devices. But right now I use the same machine for adding new stuff, so is is fine.
  Need to find a way to push my ebooks with DRM to calibre. No really needed, because Kindle app is ubiquitous, but I would like to have one central place to organize my ebooks collection.