Real-Time Voice AgentsfreemiumLimited free

Ultravox

Speech-native processing skips the STT-to-text bottleneck, preserving tone/cadence/pitch

Visit Ultravox
ℹ
Limited free tier

Only a one-time block of free call minutes, then pay per minute. Need it free right now? Try Bolna →

What Ultravox does

  • Speech-native processing skips the STT-to-text bottleneck, preserving tone/cadence/pitch
  • Free tier: 5¢/min including TTS for up to 5 concurrent calls
  • Open-weight models (fixie-ai) published on Hugging Face for research use

Ultravox — straight answers

What is Ultravox?

Ultravox is listed under Real-Time Voice Agents, in the AI Agents & Automation category on Flocci AI Tools. Speech-native processing skips the STT-to-text bottleneck, preserving tone/cadence/pitch. It is freemium — a usable free tier with paid plans above it, and it lives at ultravox.ai.

Is Ultravox free?

Partly. Only a one-time block of free call minutes, then pay per minute. If you need it free right now, Bolna does the same job for free.

Can I use Ultravox in a browser, or is there an app?

Ultravox works in a normal browser tab with no install. It is available on the web and an API. You can sign in with a Google account.

What can Ultravox do?

Ultravox does 3 things the catalog singles out: Speech-native processing skips the stt-to-text bottleneck, preserving tone/cadence/pitch; free tier: 5¢/min including tts for up to 5 concurrent calls; open-weight models (fixie-ai) published on hugging face for research use.

What is the best free alternative to Ultravox?

Bolna is the best free alternative: it does the same job and you can start without paying. Kyutai Unmute, LiveKit Agents and Pipecat also start free. The full list is on the alternatives page.

See the full list →

Ultravox alternatives

Compare all alternatives →

Vapi

Real-Time Voice Agents
freemium
  • Orchestrates STT/LLM/TTS providers of choice into one low-latency voice-agent pipeline
  • Usage-based per-minute pricing with free trial minutes included
  • SOC 2/HIPAA/PCI compliance add-ons for regulated call-center deployments
Visit

Retell AI

Real-Time Voice Agents
freemium
  • Free starting credit with no contract required
  • Supports swapping GPT, Claude or Gemini as the reasoning layer per agent
  • Batch calling campaigns plus live AI-to-human call transfer built in
Visit

Bland AI

Real-Time Voice Agents
freemium
  • All-in-one per-minute pricing bundles LLM+STT+TTS with no separate token pass-through charges
  • Free start with call credits plus an inbound number included
  • Tiered platform fees (Build/Scale) unlock lower per-minute rates for high volume
Visit

LiveKit Agents

Real-Time Voice Agents
free
  • Apache-2.0 open-source framework, fully self-hostable on your own servers
  • Native WebRTC client support across web/mobile/telephony out of the box
  • Native Model Context Protocol (MCP) support for tool-using voice agents
Visit

Pipecat

Real-Time Voice Agents
free
  • BSD-2-Clause open-source Python framework for real-time voice/multimodal agents
  • Supports distributed multi-agent systems with handoffs over a shared bus
  • Maintained by Daily with an active plugin ecosystem for STT/LLM/TTS providers
Visit

Bolna

Real-Time Voice Agents
freeNew
  • Open-source framework for phone voice agents, from an India-based team
  • Connects to telephony, STT, LLM and TTS providers of your choice
  • Supports Indian languages
  • Self-host free; hosted platform is pay-as-you-go
Visit

Head-to-head comparisons

Ultravox vs VapiUltravox vs Retell AIUltravox vs Bland AIUltravox vs LiveKit AgentsUltravox vs PipecatUltravox vs Bolna