Synth is a free podcasting tool that I’ve been recommending since its launch last fall. It provides a simple way to create short podcasts that people can reply to with their own audio comments. Think of it kind of like Flipgrid for audio.
Yesterday, Synth announced that you and your students can now download your recordings as MP3 files. You can download an individual recording or a series of threaded recordings.
Source : Free Technology for Teachers