Is there a performant JSON based DB with a client side implementation?
I found this question about SQL-like query libraries. What I am looking for is a library that allows queries on JSON objects, embedded in a client-side application (browser), as well as from a remote high performance dedicated database.
You could try couchbase lite (client side) that syncs with couchbase server.
It is a document based nosql database, querying isn't as rich as SQL but you have the ability to create additional indices on which to query your data by using couchbase views (map reduce jobs). These work both on the client and server, it also supports syncing between the device and server.
For the sake of completeness I'll throw out PouchDB and CouchDB.
I was searching for the same thing and after much searching suddenly came across NeDB, which now has a browser implementation.
Unlike PouchDB it has a Mongo-like query API.
if you want to use SQL-query you could try N1QL. This extension to Couchbase allows you to query the system very similar to SQL-query. Also you should look at ElasticSearch. This is a very powerful search engine, but query language not SQL. Couchbase and ElasticSearch very well interact with each other via the plugin. Also OrientDB allows to do query on language very similar to SQL. I think it is possible to adapt OrientDB to json format. And of course there are MongoDB.