Shortcast

Shortcast takes a long recording, such as a podcast, talk or stream, and picks three to six moments likely to work as short posts. It transcribes the audio with WhisperKit, cuts each clip, reframes horizontal footage to 9:16 by tracking the speaker's face, and writes captions for TikTok, Instagram and YouTube Shorts. Transcription and captioning run on the Mac with a local model; the video leaves the Mac only when you publish or schedule it through Upload-Post. It suits creators who post short-form video regularly.

Shortcast requires macOS 15 or later on Apple silicon; the README says Intel is not supported. The release is not notarized, so macOS blocks the first launch and you must allow it with the xattr command in the README. The first run downloads roughly 5 to 7 GB of language models and the WhisperKit model. Publishing needs an Upload-Post API key, and that service's free tier limits monthly uploads.