Fileshifter is a web based app that helps convert office documents and other file types to various formats.
Video Transcoder allows you to transcode videos from one format to another for free on your Android device.
FFmpeg is a one-stop solution to all of your recording, converting, and streaming needs for your audio and video files. It’s available for free for Windows, Mac, and Linux.
HandBrake is an open source video transcoder for Windows, Mac, and Linux.