IDA is alternative of IDM. Internet download accelerator is free and it is available in installable and portable form. Great thing about this software is this, it can download YouTube videos and videos from other streaming media websites. You can preview zip, audio, video files while downloading. You can set priorities for downloading. Many internet download managers will give all internet speed to downloading files affecting your internet browser speed but this download manager manages fair amount of speed for your browsing need while you download other stuff. Multi-language support, FTP explorer, skins, plugins support are other great features.