On-device AI vs cloud AI
Also known as: local vs cloud, edge AI
On-device AI runs the model on your own machine, so your data never leaves it; cloud AI runs it on a provider's servers, which means uploading your audio. The trade is privacy and offline use against convenience and access to larger hosted models.
Why it matters
For voice, this choice is really a choice about your data. Cloud AI uploads your audio to a server to process it, which for unreleased scripts, client work, or anything sensitive is a real consideration, not an abstract one. On-device AI keeps everything on your machine and keeps working with no connection, at the cost of being bounded by your own hardware.
Neither is simply better. The right answer depends on how sensitive the material is and how much you value working offline against reaching for the largest hosted models.
In practice
Choose by the sensitivity of the audio and your need to work offline. For private or unreleased material, on-device keeps it on your machine. For casual work where the largest cloud model helps and privacy is not a concern, the cloud is convenient.
How Vocast handles this
Vocast runs entirely on-device on Apple Silicon. Your voiceprint, scripts, and renders never leave the Mac, and it keeps working offline after the first model download.