PouchDB - The JavaScript database that Syncs

PouchDB was written to help web developers build applications that work as well offline as well as they do online, applications save data locally so the user can use all the features of an app even while offline and synchronise the data between clients so they have up to date data wherever they go.

PouchDB Example

PouchDB is Open Source, written in Javascript and inspired by Apache CouchDB, it is designed to be lightweight and easily embeddable.

Cross Browser 
PouchDB uses various backends so it can work across various browsers and in Node.js. It uses IndexedDB in Firefox and Chrome, WebSQL in Safari and Opera and LevelDB in Node.js.
Currently tested in:

• Firefox 12+
• Chrome 19+
• Opera 12+
• Safari 5+
• Node.js 0.10+
• Apache Cordova
• Internet Explorer 10+

If your application requires support for Internet Explorer below version 10, it is possible to use an online CouchDB as a fallback, however it will not work offline.

PouchDB Project Page