The 5 best voice AI APIs and infrastructure (2026)

As of October 2026, none of these states a price. Cartesia and LiveKit Agents have a free plan.

Updated 24 October 20265 AI apis2 verified in the last 30 days4 updated in that window

Prices checked 2 September–24 October 2026

Reviewed by The Agents Index editorial team.

The ones whose price, API, docs, sources and limits we could confirm come first. How we rank →

This spot is open
Featured AI apis show here and first on related and alternatives pages.
- API access: Not stated
- Free tier: Not stated
- MCP server: Not stated
- Own API key: Not stated
- Open source: Not stated
- Self-hosted: Not stated
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LiveKit Agents
Open-source Python and Node.js framework for voice AI agents, with LiveKit Cloud hosting, telephony and observability.
Free, then $50/month
From
Free, then $50/month
- API access: Yes
- Free tier: Yes
- MCP server: Partly
- Own API key: Partly
- Open source: Yes
- Self-hosted: Yes
Checked 2 September 2026
Visit LiveKit AgentsCompare LiveKit Agents
Cartesia
Real-time speech models and a managed runtime for production phone and web voice agents.
Free, then $5/month
From
Free, then $5/month
- API access: Yes
- Free tier: Yes
- MCP server: Yes
- Own API key: Partly
- Open source: Partly
- Self-hosted: Partly
Checked 2 September 2026
Visit CartesiaCompare Cartesia
Deepgram Voice Agent API
One WebSocket API that runs speech-to-text, LLM orchestration and text-to-speech for real-time voice agents.
From $0.05/minute
From
$0.05/minute
- API access: Yes
- Free tier: Partly
- MCP server: Partly
- Own API key: Yes
- Open source: Partly
- Self-hosted: Partly
Checked 2 September 2026
Visit Deepgram Voice Agent APICompare Deepgram Voice Agent API
OpenAI Realtime API
Speech-to-speech API for voice agents, with tools, MCP and WebRTC or WebSocket transport.
From $10/1m audio input tokens
From
$10/1m audio input tokens
- API access: Yes
- Free tier: No
- MCP server: Partly
- Own API key: Partly
- Open source: Partly
- Self-hosted: No
Checked 23 October 2026
Visit OpenAI Realtime APICompare OpenAI Realtime API
sipgate flow
EU-hosted real-time voice and telephony API that puts your own AI agent on the phone.
On quote
From
On quote
- API access: Yes
- Free tier: No
- MCP server: Not stated
- Own API key: Partly
- Open source: Partly
- Self-hosted: Partly
Checked 26 September 2026
Visit sipgate flowCompare sipgate flow
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Speech-to-text, text-to-speech and real-time voice APIs and frameworks that voice agents are built on.

Questions buyers ask

Which AI api here costs the least?

Cartesia and LiveKit Agents have a free plan.

Which AI apis here have a free plan?

2 of the 5: Cartesia and LiveKit Agents.

When were these prices checked?

Between 2 September 2026 and 24 October 2026, each read on the maker's own pricing page.

Sources and method

How we rank

Every price here was read on the maker's own pricing page.

Cartesia: cartesia.ai/pricing, checked 24 October 2026
Deepgram Voice Agent API: deepgram.com/pricing, checked 2 September 2026
LiveKit Agents: livekit.com/pricing, checked 24 October 2026
OpenAI Realtime API: developers.openai.com/api/docs/pricing, checked 23 October 2026
sipgate flow: flow.sipgate.io, checked 26 September 2026

All Voice AI APIs

LiveKit Agents

Cartesia

Deepgram Voice Agent API

OpenAI Realtime API

sipgate flow

Questions buyers ask

Which AI api here costs the least?

Which AI apis here have a free plan?

When were these prices checked?

Sources and method