Hello WebApps Group, For the past few years sites have been enabling directory uploads by using the old FileSystem API  in Chrome and Opera. In the April 2014 face to face WebApps group meeting , there was a CfC to move the old specs into a WG Note and to continue working on the new FileSystem API  instead, effectively discontinuing work on the old FileSystem API.
The new FileSystem API tries to satisfy a large number of use cases with an approach that is better than the old API. However, its broad scope and its dependencies on future capabilities (e.g. Observables) has slowed down the pace at which it is moving forward. Due to this, there is currently no interoperable way to enable directory uploads on the web. We have received lots of feedback from developers - including some working on Microsoft services such as OneDrive - that supporting directory upload is a high priority for them. To enable developers to build future interoperable solutions, we've drafted a proposal , with the helpful feedback of Mozilla and Google, that focuses strictly on providing the mechanisms necessary to enable directory uploads. The proposal uses a subset of the new FileSystem API so that it can be expanded in the future to enable more scenarios when the new FileSystem API is further along. To help understand the proposal (especially the APIs involved) I have written a polyfill  and demo page  that is built on top of Chrome's old FileSystem API. If there is sufficient interest, I would like to work on this within the scope of the WebApps working group. Thank you, Ali  Old FileSystem API: http://www.w3.org/TR/file-system-api/  WebApps April '14 Meeting: http://www.w3.org/2014/04/10-webapps-minutes.html#item02  New FileSystem API: http://w3c.github.io/filesystem-api/  Proposal: http://internetexplorer.github.io/directory-upload/proposal.html  Polyfill: https://github.com/InternetExplorer/directory-upload/blob/gh-pages/polyfill.js  Demo: http://internetexplorer.github.io/directory-upload/index.html