If you're building a product on open-source text-to-speech, the licence file deserves more of your attention than the demo audio. I learned this the slow way while picking models for a desktop app, and the specifics are worth writing down because the most popular option in the category is also the one you probably can't ship.

The three models worth knowing about.

Kokoro-82M — 82 million parameters, Apache 2.0, eight languages and fifty-four preset voices. It does not clone voices; you pick from its voice list. What it gives you instead is the ability to run on an ordinary CPU without a GPU anywhere in sight, which no other model here manages comfortably. For narration, app prompts, accessibility features, it's the obvious answer and the licence is the most permissive in the group.

XTTS-v2 — Coqui's model, seventeen languages, clones from a roughly six-second reference clip per its own model card. It is, by a distance, the one people search for and the one most tutorials cover.…