PouchDB

PouchDB is an open source, pocket-sized JavaScript database that conveniently synchronizes with servers when it gets back online. It’s inspired by Apache CouchDB, so it’s designed to run well within the browser.

PouchDB was created to enable web developers to build applications that will work just as well offline as they do online. It enables applications to store data locally while offline, and once back online it will synchronize with CouchDB and compatible servers, so your data will always be in sync.

PouchDB works on various browsers, including Chrome, Firefox, Safari and more. It’s very lightweight and though some programming knowledge is required, is still very easy to learn.