title_body: Online ebooks management system that can be hosted on a server
upvoted_answer: I am not sure why you would need to run this on a web server; if it is just for backup reasons and distributed access I would just push the folder in one of the common online storage solutions like Dropbox or similar.
  
  Calibre can be run as a server itself and offer the files in its library via a web interface. You can then access the files via the web browser of your reader. It works, but if you have access to a computer where you can use Calibre directly I think it is much more practical by several orders of magnitude.
  
  But your specifications are not specific enough to tell if this solution fits your needs.
  
  Google Play Books allows you to upload your own books so you could use this for synchronisation and distributed access also.