CouchDB : Apache CouchDB™ is a database
that uses JSON for documents,
JavaScript for MapReduce indexes,
and regular HTTP for its API
Kinto : Kinto is a lightweight JSON storage service with synchronisation and sharing abilities.
LokiJS : A fast, in-memory document-oriented datastore for node.js, browser and cordova
localForage : localForage is a handy library that improves the offline experience of your web app by using asynchronous storage (via IndexedDB or WebSQL where avail...
A Lawnchair is sorta like a couch except smaller and outside. Perfect for HTML5 mobile apps that need a lightweight, adaptive, simple and elegant persistence solution.