> Mobile support: CouchDB stands out, in that it can run on an Android or iOS mobile device. In addition to being mobile, the database can also synchronize with a remote master database, allowing the data to be shared easily between mobile devices and servers.<p>Meteor actually provides exactly this for MongoDB; it has a "minimongo" package in the browser that supports Mongo's query language, running it synchronously against an in-memory copy of the collection [0]. And with Meteor, you can specify "subscriptions" declaratively that enable bidirectional synchronization while their owner components are in scope.<p>Mongo certainly has some reliability issues (see other comments here) but I've yet to find a full-stack system so painless to develop in, <i>especially</i> if you need realtime support. With things like ToroDB Stampede [1] and a general approach of "write all your code in React with Meteor dependencies factored out into containers," there's a clear migration path towards the relational-based separate-backend-frontend world when you need to go there.<p>[0] <a href="https://guide.meteor.com/collections.html" rel="nofollow">https://guide.meteor.com/collections.html</a><p>[1] <a href="https://www.torodb.com/stampede/docs/1.0.0-beta2/about/" rel="nofollow">https://www.torodb.com/stampede/docs/1.0.0-beta2/about/</a>