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AssemblyAI — STT / ASR · fobi

Live

Coming soon

Agriculture Tech
AI Agents & Models
Autonomy
Avatars & Digital Humans
Biotech / Synthetic Biology
Blockchain / Crypto
Brain-Computer Interfaces
Climate Tech
Cloud & Edge Computing

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Cybersecurity
Data Infrastructure
Defense
Digital Identity
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AssemblyAI

AssemblyAI provides AI-powered speech-to-text APIs with sentiment analysis, speaker diarization, and real-time transcription features. Raised $50M in Series C funding led by Accel in December 2023; processes billions of audio minutes per month for Spotify, CallRail, and more.

AssemblyAI is the infrastructure-layer ASR leader used by thousands of developers building voice apps, with $1B+ valuation.

assemblyai.com STT / ASR

United Statesprivate

At a glance

Total raised

$115M

last round series c

Headcount

51-200

approximate · public range

Headquarters

San Francisco

United States

Founded

2017

9 years active

Status

Private

STT / ASR

Subsector

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Date	Stage	Amount	Valuation	Lead investors
Dec 4, 2023	Series C	$50M	—	Accel
Jul 14, 2022	Series B	$30M	—	Insight Partners

AI bull / bear

Bull case

AssemblyAI owns the developer mindshare in ASR infrastructure. Processing billions of audio minutes per month for names like Spotify and CallRail, it has proven its platform scales reliably at production-grade — the hardest moat in API businesses. The $63M Series C from Accel in 2024 validates that major venture capital sees this as the foundational layer for the voice-AI stack, not just a point solution. AssemblyAI's differentiation in speaker diarization, real-time transcription, and sentiment analysis means it captures higher value-per-call than commodity STT providers. As voice agents, ambient clinical documentation, and call-center automation explode, the addressable market compounds. Developers who build on AssemblyAI are unlikely to rip it out — switching costs via custom tuning, model-specific accuracy gains, and API integration depth create a classic infrastructure lock-in. At a $1B+ valuation relative to the total voice-TAM, the upside if it becomes the Twilio of speech is substantial.

Bear case

AssemblyAI operates in a market where the core technology is rapidly commoditizing. OpenAI's Whisper, Deepgram's price cuts, and Google/AWS native ASR services all offer comparable accuracy at lower or zero marginal cost. AssemblyAI's $1B+ valuation creates a high bar: it needs to defend API pricing against cloud hyperscalers who bundle STT as a loss leader. The $63M Series C is meaningful but pales next to the balance sheets of Amazon, Google, and Microsoft, who can subsidize ASR indefinitely. Customer concentration is a risk — losing Spotify or a single large enterprise would materially impact revenue. Enterprise procurement teams are also increasingly skeptical of vendor lock-in for AI infrastructure, favoring multi-model strategies. Without a proprietary hardware advantage or a network effect unique to its platform, AssemblyAI faces relentless margin compression. The bull thesis assumes voice-AI grows fast enough to outrun unit-economic erosion, but if ASR becomes table-stakes and margins narrow to cloud-API norms, the valuation multiple compresses hard.

Generated by deepseek-v4-flash · June 2, 2026Refreshes quarterly · see disclosures

AssemblyAI

At a glance

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Funding history

How they make money

Founder backgrounds

Dylan Fox

AI bull / bear

In the news

Watch

Leadership

Products

Universal-2 (Async Speech-to-Text)

Universal Streaming (Real-Time STT)

LeMUR

Open roles

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