An Airvoz alternative for long texts, offline
Airvoz is a free online text to speech site with more than 500 voices in over 100 languages, MP3 downloads and batch conversion, and its FAQ allows the audio in videos, podcasts, courses and audiobooks. Each request takes up to 3,000 characters, so a longer text has to be split into parts and generated part by part.
If you voice chapters, long scripts or many files, the free SuperClonica engine does it on your own computer, offline, with no length limit per file. This guide compares the two honestly.
Try a voice online first
On the page of any voice in the catalog, paste a line you voiced with Airvoz, 30 to 100 characters, choose the language and press Voice it. In a few seconds you can compare, with no account.
Voice a whole file in one go
Install the engine once with python -m pip install superclonica-cpu; it runs on Windows, macOS and Linux on an ordinary processor and works offline after the one-time model download. Then a whole text file is one command: superclonica --text-file chapter.txt --voice M3 --lang en --normalize --output chapter.mp3. The engine splits long texts at sentence boundaries itself and joins the result into one file.
From code
The SuperClonica speech API takes up to 20,000 characters per request and returns the audio file. A free key gives 3 minutes of audio a day with no card; paid plans start at $5 a month. Examples for curl, Python and Node.js are in the free-tts-api repository on GitHub.
Where Airvoz is stronger
Airvoz covers many more languages, including Chinese, Bengali, Afrikaans and others Supertonic 3 does not speak, and needs nothing installed. For short clips in those languages it is the simpler choice. SuperClonica speaks 31 languages and is strongest for long or repeated voicing, offline privacy, and catalog voices: narrators, announcers and characters.
Voices and rights
The ten stock voices, M1 to M5 and F1 to F5, may be used commercially under the OpenRAIL-M model license, and so may a voice trained from your own recording. Character voices in the catalog are fan-made, for fan and parody use only. Some catalog voices are paid, bought once.