Pluploader is the most powerful client-side upload library out there and it would be a shame, if the Vaadin community couldn't use it. The license concernes olny the addon. If You want to use Plupload, please familiarize youself with it's licensing terms. Why is this add-on worthy of Your interest? - Live upload progress updates without any needs of Push dependencies or enabled asyncSupported feature (no polling either). - Chunked uploads with direct streaming to the desired destination - meaning that You can upload gigabyte-sized files without worrying about memory (RAM) usage on the server part, and if something goes wrong with the network the uploader will try to send the chunk again. You can also pause the upload and resume it, when network problems are resolved. - Many events and event handlers give You the ability to respond dynamically to almost every situation - 3 different compontents with 3 different purposes and complexity levels - choose the right one and customize it to Your needs How is all this possible? The Plupload library (on the client side) controls the upload process and sends appropriate events, which are propagated to the server side through RPC. The server side can respond accordingly and control the upload process this way, or update the UI components. All the chunking and resizing (in case of images) is done on the client side. All server side has to do is implement some event handlers. About the Browser compatibility: I've selected only the browsers, that I've tested this addon on, but there is a pretty good chance, that it will work on the others too... This is a fairly new code and it's not properly polished yet, so there is a serious possibility that something can go wrong somewhere. Don't get angry, just submit an issue, or work on the problem and submit a pull request. The Addon doesn't currently work with Portlets. If anybody would like to submit PR for that, feel free to do it :)