It depends on what you want to convert, eg; you want to convert a video file on your computer to MP4 or MP3, or a video from an online video sharing website like YouTube, Vimeo and others. There are a lot of good online video converters out there mostly for converting video from video sharing sites like youtube to MP4 and MP3 or facebook video to mp4. A simple Google search will return hundreds of them, eg. few ones that returned after a search on google are video-converter-mp4 .com fierceonlinevideo .com utubemp4 .com like I said it depends on what exactly you want to convert so make google your friend :)