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Voice agents vv0.7 2026 Rank: #2901

Ultravox.ai ✓

Speech-native voice AI agents

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Open Source s2s Speech Native Voice agents
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Verdict

A quick read before you dig into the full page.

Best if
Speech-native voice AI agents
Skip if
Adaption to new languages might be limited
Pick this when
Bypasses text conversion

Considering Speechmatics | AI Voice Agents instead? Compare side by side

Overview

Ultravox is a real-time voice AI platform for building fast, fluent conversational experiences.

With developer-friendly APIs, agentic-ready primitives, and a speech-native model, Ultravox makes it easy to build voice agents that follow instructions reliably, interact with third-party systems effectively, and communicate naturally.

Legacy voice AI systems orchestrate a series of independent component services that form a connected pipeline, which is subject to unpredictable latency. Ultravox controls and manages our entire inference stack and infrastructure, so we can guarantee reliability and availability at scale.

Each voice AI call through Ultravox Realtime is assigned dedicated GPU resources for the entire lifespan of the call, ensuring a consistent low-latency experience regardless of demand on our system, even for users with thousands of concurrent calls.


Join thousands of teams building natural, conversational voice AI agents with Ultravox.
Ultravox.ai website

Access & connections

Where you can use Ultravox.ai.

Platforms

Web

API

Public API available

Browse other tools with an API

Capabilities

What this tool accepts, produces, and is strongest at.

Input

  • API
  • Text
  • Audio

Output

  • Audio
  • API
  • Text

Highlights

  • Agents
  • API
  • Open Source

Supported features

  • Agents
  • API
  • Open Source
  • Speech API

Pros & cons

Pros

  • Open-source
  • Bypasses text conversion
  • Web, native apps, telephone integrations
  • SDKs for major languages
  • Built-in Twilio support
  • Multi-language proficiency
  • Adapts new languages/accents
  • Allows any open-source model
Show 12 more
  • Allows personal models
  • Direct speech recognition
  • Reliable and faster interactions
  • Fully customisable
  • Support for additional languages
  • Unique custom voices
  • High quality speech
  • Function calling feature
  • Voice cloning
  • RAG Support
  • Works with text-based prompts
  • Captures non-textual speech elements

Cons

  • Might struggle with dialects
  • Integration complexity in non-open source
  • Customization requires technical know-how
  • Adaption to new languages might be limited
  • Accuracy varies with accent

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Releases 2

Ultravox.ai v0.7 Mar 30, 2026 Current

In the v0.7 series, the Ultravox model is trained on GLM 4.6, taking the lead on audio reasoning tasks over closed source models like gpt4o-audio, while retaining advantages in speech understanding from previous versions.

Ultravox is a multimodal model that can consume both speech and text as input (e.g., a text system prompt and voice user message). The input to the model is given as a text prompt with a special pseudo-token, and the model processor will replace this magic token with embeddings derived from the input audio. Using the merged embeddings as input, the model will then generate output text as usual.

Initial release August 30, 2024
Initial release of Ultravox.ai.

FAQ 12

What is Ultravox.ai?
Ultravox.ai is an open-source Speech Language Model (SLM) designed to understand and process speech in a similar manner to human interaction. This software excels in analyzing spoken language directly, bypassing the conventional text conversion process to enable more natural and fluid conversations. Ultravox can be integrated into web, native apps, or telephone-based products and supports multiple languages, allowing for smooth communication across diverse audiences. It can be customised extensively, enabling the addition of additional languages, fine-tuning on personal datasets, and creation of unique custom voices.
How does Ultravox.ai understand and process speech?
Ultravox.ai understands and processes speech by analyzing spoken language directly. It bypasses the conventional process of converting speech into text, allowing it to achieve more natural and fluent interactions. Its unique approach distinguishes it from typical voice systems that rely heavily on text conversion.
What platforms can integrate with Ultravox?
Ultravox can be integrated into various platforms including web-based, native apps, or telephone-based products. Its versatility and simplicity make it a perfect fit for diverse product types.
Does Ultravox support SDKs for all major languages?
Yes, Ultravox supports Software Development Kits (SDKs) for all major languages. The platform is built with broad compatibility and ease of integration in mind, enabling it to connect with a variety of programming languages.
How does Ultravox handle multi-language proficiency?
Ultravox boasts multi-language proficiency to ensure smooth communication across diverse audiences. Its sophisticated language processing capabilities enable it to fluently understand and respond in all major languages, making it suited for global applications.
Can Ultravox adapt to new languages or accents?
Yes, Ultravox has the capability to adapt to new languages or accents. Thanks to its adaptive learning feature, Ultravox ensures smooth and effective communication, even when dealing with new language inputs and varying accents.
How can Ultravox integrate with other open-source models?
Ultravox.ai provides the flexibility to work with any open-source model. This includes personal models that have been finely tuned. It’s designed to accommodate a wide range of third-party models, promoting flexibility and diverse use cases.
What makes the speech recognition of Ultravox different from other voice systems?
Unlike other voice systems that rely on transforming speech into text, Ultravox integrates speech recognition directly. This approach makes it faster, more reliable, and enables more natural interactions. It reduces the project’s overall complexity and can capture the nuances of speech more accurately.
How can Ultravox be customised to specific needs?
Ultravox can be fully customised to align with specific needs. It’s open to adding support for additional languages, fine-tuning based on personal datasets, or creating unique custom voices. This customization capability ensures a more personalized and effective user experience.
What's the process for adding support for additional languages to Ultravox?
The process of adding additional languages to Ultravox involves customization of the base model to include the new language. However, the website does not provide explicit detailed instructions or the exact process for this.
How can I fine-tune Ultravox on my personal datasets?
Fine-tuning Ultravox on personal datasets would likely involve appending or training the model with the additional data. The explicit method or instructions to achieve this are however not outlined on their website.
Can I create unique custom voices with Ultravox?
Yes, Ultravox can be used to create unique custom voices. This customization capability is inherent in its design, allowing for a more individualized and tailored user experience.
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