Dropbox’s Datastore API, which gives apps a lightweight cloud database for storing structured user data, like settings and contacts, has been extended to let apps store data locally if users aren’t logged into Dropbox.

The Datastore API now also lets users share their data with others, and has a new feature designed to simplify and improve how web apps get notified about changes in the data repositories, Dropbox announced Wednesday.

“This is the biggest update to the Datastore API we’ve made since launching it last year,” said Leah Culver, Dropbox developer advocate.

The Local Datastores feature, in preview mode since June and now ready for prime time, lets apps collect data from users who aren’t signed into Dropbox, and then ships it to the cloud and syncs it across devices once they log in. The API now also lets developers configure their apps so that users share their data with other Dropbox users.

Finally, Dropbox is extending its “webhooks” functionality for files to these data respositories. Developers will be able to register a webhook URI for their app so that it will notified in real-time about changes to users’ data stores, as opposed to the app having to periodically poll Dropbox.

Although third-party developers have built more than 300,000 applications for Dropbox, the company still sees opportunities for them to take advantage of, especially in categories like mobile and social networking, both of which should benefit from the Datastore API improvements, Culver said.

Dropbox announced the Datastore API in July of last year, describing it as “simple databases for your apps with Dropbox sync built-in.”