When SlickUpload 5 was introduced, no browsers supported multiple selection or file drag/drop natively. The only solution for these was to use an often buggy ActiveX/Flash/Java plugin. Recently, browsers have started implementing multiple file selection with the HTML5 file API standard. Currently, the recent versions of Chrome, Firefox, and Safari all support multiple file selection and file drag/drop.

Implementing multi-select and drag/drop was a big goal of our development effort for SlickUpload 6. To support this, we refactored SlickUpload to upload each file individually, whether it was multi-selected or not. This means that you can do GMail style file-by-file uploads in all browsers. SlickUpload implements multiselection in browsers that support the HTML5 API, with single selection as a fallback. This also means that each file is treated separately when calculating maximum upload size. Before, you could only upload a total of 2GB-4GB (depending on IIS version). Now, you can upload 2GB-4GB per file (depending on IIS version), with an unlimited total upload size.

Multiple file selection

File drag/drop

We also implemented client side file size detection for all browsers. In HTML5 compliant browsers, this uses the file size attributes to immediately display file size. For non-compliant browsers, SlickUpload will ping the server to determine file size. The file isn't uploaded, but the file size is detected. This means you can also validate file size client side before an upload.

GMail style individual file upload