MIME Type Validation

Demo uploads land in a temporary store and are swept after 60 minutes. To keep files, handle FileUploaded — see Single File for the complete save pattern.

Validate files by their MIME type using EnableMimeCheck="true". This checks the actual content type rather than just the file extension, providing stronger security.

What you should see: the file's real content type is checked (magic bytes), not just its extension - rename a .txt to .jpg and it is still caught.

Drag & drop files here, or paste from clipboard

<au:AjaxFileUpload ID="Uploader1" runat="server"
 EnableMimeCheck="true"
 AllowedExtensions=".jpg,.png,.gif,.pdf"
 ButtonText="Select File (images/PDF only)"
 AutoUpload="true"
 ShowProgress="true" />

MIME checking verifies the actual file content matches the extension, preventing renamed files from bypassing extension-based validation.