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Stack Layer

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Best Speech-to-Speech Tools for Voice AI

Realtime models that listen and respond in audio without a separate STT/TTS step.

All layers

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UNIO EDITORS’ PICKS

Speech-to-Speech

Hume AI

Empathic voice interface that responds to tone and emotion in real time.

Ultravox

Open-weight speech-native model that understands audio directly, with a hosted voice API.

All Speech-to-Speech companies

Dino Dial

Orchestration & Agent Platforms

Speech-to-speech agent-building CLI.

+Orchestration

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India-ready

]

Dino Dial

Orchestration & Agent Platforms

Speech-to-speech agent-building CLI.

+Orchestration

[

India-ready

]

Gnani.AI

Orchestration & Agent Platforms

Own speech models and enterprise agent platform.

+Realtime +Orchestration

[

India-ready

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Gnani.AI

Orchestration & Agent Platforms

Own speech models and enterprise agent platform.

+Realtime +Orchestration

[

India-ready

]

Google Gemini

LLM / Reasoning

Gemini models, including the Live API for low-latency voice conversations.

+Realtime

[

India-ready

]

Google Gemini

LLM / Reasoning

Gemini models, including the Live API for low-latency voice conversations.

+Realtime

[

India-ready

]

Hume AI

Speech-to-Speech

Empathic voice interface that responds to tone and emotion in real time.

Hume AI

Speech-to-Speech

Empathic voice interface that responds to tone and emotion in real time.

OpenAI

LLM / Reasoning

GPT models and the Realtime API, used as the reasoning layer in many voice agents.

+Realtime

OpenAI

LLM / Reasoning

GPT models and the Realtime API, used as the reasoning layer in many voice agents.

+Realtime

Ultravox

Speech-to-Speech

Open-weight speech-native model that understands audio directly, with a hosted voice API.

+Orchestration

Ultravox

Speech-to-Speech

Open-weight speech-native model that understands audio directly, with a hosted voice API.

+Orchestration