What kind of database do apps like Snapchat, Instagram, etc. use to store pictures and info. I'm guessing it is not MySQL, or Firebase, or Parse, so then what is it.

It's probably as quick to use file system if you could never the users and dates to strings and store them that way?

chances are it's a nosql database like mongodb, couchdb, or Cassandra.

@sheffters is probably right. No sense putting them in a db

Some use google app engine, others use Amazon web services, snapchat is built using googles cloud

@bobotay well image storage wise you are right, but as for the metadata it would take too long to scrape a thousand pictures along with the added benifit of being able to off load storage space by adding an access url in that metadata

@jckimble yeah my guess is fs for photos with links to them in postgres

Possibly a graph database. It would manage network reqs better than a relational db. Possibly Neo4j