Speech-to-text for AI voice agents

Agent STT runs on Linden 1, a model purpose-built for AI voice agents. It accurately captures what was said and by who in under 300ms. From $0.30/hour.

Start with $100 in free credit.

Use it through LiveKit, Pipecat, or the API directly.

Case study

AI Media | Case study

Delivering 120X more with voice AI

Powering live content through AI-powered transcription, built on industry-leading voice AI

Case study

LiveKit | Case study

Enabling 100,000+ developers with leading speech recognition

Pairing LiveKit’s flexible agent framework with Speechmatics to build world-class agents

Case study

NCI | Case study

Redefining real-time captioning

How NCI delivered a 99% increase in usage of automated captioning

Case study

Media Track | Case study

Delivering a 20% leap in accuracy improvements

Improved transcription performance across more than 20 languages for their global clients

Case study

Prosodica | Case study

Driving better conversations at scale

Leveraging speech recognition to track customer interactions, highlight key insights, and raise contact center performance

Built for what AI voice agents need

Not a general-purpose transcript. Accuracy, speed, and signal, tuned for the moments a voice AI agent can’t afford to get wrong.

Accuracy

Catches the details that matter

Linden 1 transcribes 55+ languages and catches names, numbers and details that general models miss, so your agent acts on what was actually said.

Languages

Latency

Final transcripts in under 300ms

End-of-speech finalization lands in under 300ms, giving your LLM more time to draft a reply before callers notice the pause in the conversation.

Latency docs

Speaker focus

Knows exactly who is talking

Speaker diarization attributes every word to the person who said it, so your agent acts on the right voice, not the loudest one, in multi-speaker calls.

Speaker diarization docs

Price

$0.30 an hour to start

Linden 1 costs $0.30/hour at launch, with volume discounts that bring the price down to $0.15/hour as your usage scales, and no change to accuracy or latency.

Full pricing

Accuracy gains, measured

Character sequence accuracy (English)

55.6% → 96.9%

Digit sequence accuracy

73.2% → 98.0%

German digit sequences

60% → 93%

Speechmatics is the most accurate STT for voice agents, per Pipecat’s public benchmark.

How to build with Agent STT

Agent STT drops into the voice agent stack you already use, or straight into your own pipeline. Pick the level of control you need.

Path	Best for	How it works
LiveKit	Fastest to launch	Select Linden 1 in LiveKit Inference. One config change or a toggle in the LiveKit UI, no new account or SDK.
LiveKit Agents & Pipecat	Full control in code	Open-source framework, pre-built Agent STT integration for LiveKit Agents and Pipecat. Proven pattern, no build from scratch.
Direct API	Maximum control	Connect to /v2/agent with your existing Speechmatics API key and model linden-1. Build your own STT, LLM, and TTS pipeline.

Build AI voice agents faster with a flexible API

Build AI voice agents without rebuilding the speech layer from scratch. Speechmatics gives teams a flexible API for accurate, low-latency transcription. Developers can focus on the agent experience, workflow logic, and what happens after the conversation.

Or build on the voice agent frameworks you already use.

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# ILLUSTRATIVE ONLY — confirm exact SDK syntax with the docs team before publishing.
# Agent STT connects over the /v2/agent endpoint using model "linden-1".
import os
from speechmatics.rt import AsyncClient, AudioFormat, AudioEncoding

async def main():
    client = AsyncClient(api_key=os.getenv("SPEECHMATICS_API_KEY"))
    async with client:
        await client.start_session(
            transcription_config={"model": "linden-1"},
            audio_format=AudioFormat(
                encoding=AudioEncoding.PCM_S16LE,
                sample_rate=16000,
            ),
        )
        # Agent STT emits AddSegment / AddPartialSegment plus
        # Speech and Turn start/end events on this endpoint.
        async for message in client.messages():
            print(message)

What does Linden 1 cost?

Linden 1 is the speech-to-text model behind Agent STT, built for voice agents rather than general transcription. Speaker diarization and turn signals are included by default.

It costs $0.30/hour at launch (list $0.40/hour), with volume discounts as usage scales down to $0.15/hour. A calculator for modeling your own usage is coming soon.

Agent STT: Frequently asked questions

Agent STT is a speech-to-text API and model built for voice agents. It runs on Linden 1, adds custom vocabulary, and tells your agent who's speaking, all in under 300ms.

Agent STT runs on Linden 1 today and is available in all 55+ languages. Full multilingual support is coming soon.

Agent STT gives you voice activity and turn signals (start of speech, end of speech, start of turn, end of turn) today, driven by silence detection. Server-side semantic turn detection is coming soon.

Agent STT is a separate package priced and built specifically for voice agents, with turn and speaker signals included. It's not a replacement for general-purpose real-time transcription.

LiveKit and Pipecat today, or connect directly through the API.

$0.30/hour at launch (list $0.40/hour), with volume discounts as usage scales.

Data is sent to either our EU or US endpoints. Customers can also use our Global endpoint which routes you to the nearest location and improves latency.

Yes. Custom Dictionary is fully supported. Add up to 1,000 words to accurately capture place names, acronyms, or any other business-specific vocabulary.

Build voice agents that don't get the details wrong.

Speech-to-text for AI voice agents

Delivering 120X more with voice AI

Enabling 100,000+ developers with leading speech recognition

Redefining real-time captioning

Delivering a 20% leap in accuracy improvements

Driving better conversations at scale

Built for what AI voice agents need

Built for what AI voice agents need

Catches the details that matter

Final transcripts in under 300ms

Knows exactly who is talking

$0.30 an hour to start

Accuracy gains, measured

Accuracy gains, measured

55.6% → 96.9%

73.2% → 98.0%

60% → 93%

How to build with Agent STT

How to build with Agent STT

Build AI voice agents faster with a flexible API

What does Linden 1 cost?

Agent STT: Frequently asked questions

What is Agent STT?

Does Agent STT support multiple languages?

Does Agent STT detect end of turn or handle interruptions?

How is Agent STT different from Speechmatics real-time transcription?

Which frameworks does Agent STT work with?

How much does Agent STT cost?

Where is data stored?

Does Agent STT support custom dictionary?

Build voice agents that don't get the details wrong.