ItoTTS: two natural English voices in 4.89 MB for a $5 ESP32-S3

Hi everyone! I'm part of the Lokutor team. Last week we presented Oído here, and the response was amazing. We've received dozens of videos and messages from you guys saying you love it. Thank you!

Now we're back with the next part of our plan: ItoTTS, a natural-sounding, streaming TTS engine for the ESP32-S3. Two English voices, 24 kHz audio, and 4.89 MB of weights per voice. The goal: give your local LLM a voice on a $5 chip.

In our automatic naturalness evaluation, Ito beats the ESP32-compatible TTS models we compared against. Here are the UTMOS scores on eight held-out sentences:

Teacher (StyleTTS 2): 4.49

Ito: 4.46

sanoTTS amy: 3.98

sanoTTS heart-nano: 2.07

This is a small automatic evaluation, not an independent listening study or proof that everyone will prefer Ito. Listen to the samples and tell us what you think. The demo uses the host engine's output, verified bit-identical to the firmware in QEMU. We haven't measured speed on a physical board yet, and text-to-phoneme conversion currently runs on the host.

Code: https://github.com/lokutor-ai/ito
Model weights: https://huggingface.co/lokutor-ai/ito
Demo: https://lokutor-ai.github.io/ito/

The code is open source under GPLv3. The weights are free for non-commercial use under CC BY-NC-SA 4.0 plus terms, with access through Hugging Face. They aren't unrestricted open-source weights.

We chose this license because we don't want big corporations to take our work and crush us. We need to protect ourselves, but we're very open to collaborations with individuals and small companies without charging a license fee. Commercial use still needs a separate written agreement.

Send us your videos or reviews if you try it. We're around and would love to see what you build!