Methods and systems for background uploading of media files are presented that greatly improve efficiency and user-experience in creating media-based projects. In one embodiment, a user selects original media files at a user-device for an upload. The user-device first resizes the original files to resized files and uploads them to a server, and second the original files start uploading in a background computer process. The server then allows the user to create, edit, manipulate, and even finish building the project without having to wait for the original files to upload completely, during which time the user-device gives the user an illusionary impression of a completed upload, even while the original files are still uploading. Finally, the user-device completes the upload of the original files to the server, either while the user is editing the project, or after the user has completed editing the project using an upload widget.