AssemblyAI
AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications.
What AssemblyAI is
AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications. Its Speech Understanding API includes speaker diarization and identification, summaries, action items, sentiment analysis, key phrases, entity and topic detection, formatting, language detection, translation, PII redaction, and content moderation. The platform states that it covers 99 languages and translates into 86. It offers managed-cloud use or self-hosting inside a customer’s environment, with API access and integrations including Twilio, Zoom RTMS, Zapier, LangChain, and Vercel AI SDK. Documentation includes Python and JavaScript SDK guidance. Listed protections include TLS 1.2+ encryption in transit, AES-256 encryption at rest, zero data retention, and an option to opt out of model training. AssemblyAI states that streaming and voice-agent latency is below 300ms. A free tier is available, and usage-based plans are billed monthly. Listed rates include $0.15 per hour for Universal-2 and $0.45 per hour for Universal-3.6 Pro Realtime. Free credits include $50 in audio credits, subject to connection and transcription limits.
Good
- Covers 99 languages and translates into 86
- Includes speaker identification and diarization
- Supports managed cloud or self-hosting
- Offers Python and JavaScript SDK guidance
- Free tier includes $50 in audio credits
Watch out
- Free tier limits streaming connections and concurrent transcriptions
- Universal-3.6 Pro Realtime costs $0.45 per hour
- Universal-3.5 Pro supports 18 languages
Who it suits
It suits developers building speech-to-text or voice applications who want API access, multiple speech-understanding features, or self-hosting. The available SDK guidance is relevant to Python and JavaScript developers.
Verdict
AssemblyAI offers a broad set of speech and language features through APIs, with managed and self-hosted deployment options. A free tier is available, while paid rates depend on the selected model and usage.
Plans and prices
From AssemblyAI's own pricing page, checked 20 Sep 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Free credits | Free | $50 in audio credits · 5 new streaming connections per minute · 5 concurrent pre-recorded transcriptions |
| Pay as you go — Universal-2 | $0.15 a month | 99 languages · 200+ concurrent pre-recorded transcriptions · Billed monthly based on actual usage; audio is prorated to the second |
| Pay as you go — Universal-3.5 Pro | $0.21 a month | 18 languages · 200+ concurrent pre-recorded transcriptions · Billed monthly based on actual usage; audio is prorated to the second |
| Pay as you go — Universal-Streaming | $0.15 a month | 5 new streams per minute on free accounts · 100+ starting sessions per minute on paid accounts · Billed monthly based on actual usage |
| Pay as you go — Universal-3.5 Pro Realtime | $0.45 a month | 18 languages · 100+ starting sessions per minute on paid accounts · Billed monthly based on actual usage |
| Free tier | Free | Up to 185 hours pre-recorded transcription · up to 333 hours streaming transcription · 5 new streaming connections per minute |
| Universal-Streaming | $0.15 a month | English-only realtime transcription · per hour of audio |
| Universal-2 | $0.15 a month | 99 languages · lower-price speech-to-text model · per hour of audio |
| Universal-Streaming Multilingual | $0.15 a month | English, Spanish, German, French, Portuguese, and Italian · per hour of audio |
| Universal-3.5 Pro | $0.21 a month | 18 languages · custom rate limits available · per hour of audio |
| Universal-3.6 Pro Realtime | $0.45 a month | 32 languages · context carryover and conversation memory · per hour of audio |
| Voice Agent API | $4.50 a month | Managed orchestration and hosting · no per-layer add-ons or concurrency fees · per hour of connected conversation time |
| Custom | Priced on request | Custom rate limits · enhanced concurrency · enterprise flexibility |
The facts
Each one read from AssemblyAI's own pages, with the date it was checked.
What it does
- API access
- Yeschecked 20 Sep 2026
- Compliance
- AssemblyAI maintains an annually audited SOC 2 Type 2 report and conducts annual third-party penetration tests.checked 1 Oct 2026
- Deployment
- Customers can run AssemblyAI in its managed cloud or self-host the models inside their own environment.checked 1 Oct 2026
- Developer support
- AssemblyAI provides documentation, an API reference, cookbooks, support resources, a changelog, and a service-status page.checked 1 Oct 2026
- Export formats
- SRT,VTTchecked 20 Sep 2026
- Integrations
- Official integrations include LiveKit, Pipecat, OpenRouter, Zapier, Make, n8n, Postman, Recall.ai, Zoom RTMS, Telnyx, Twilio, Amazon Connect, Genesys Cloud, LangChain, Vercel AI SDK, Power Automate, Semantic Kernel, Cloudflare, Bubble, Pipedream, and Drupal.checked 1 Oct 2026
- Language coverage
- The platform states coverage across 99 languages and translation into 86 languages.checked 1 Oct 2026
- Languages supported
- 99checked 20 Sep 2026
- Latency
- AssemblyAI states sub-300ms latency for streaming and voice agents.checked 1 Oct 2026
- Scale
- AssemblyAI states that its platform processes more than 800 million API calls per month.checked 1 Oct 2026
- SDKs
- Official documentation provides Python and JavaScript SDK guidance.checked 1 Oct 2026
- Security
- AssemblyAI offers TLS 1.2+ encryption in transit, AES-256 encryption at rest, zero data retention, and an opt-out from model training.checked 1 Oct 2026
- Speaker identification
- Yeschecked 20 Sep 2026
- Speech features
- Its Speech Understanding API supports speaker diarization, speaker identification, summarization, action items, sentiment analysis, key phrases, entity detection, topic detection, formatting, language detection, translation, PII redaction, and content moderation.checked 1 Oct 2026
- Timestamp support
- Yeschecked 20 Sep 2026
- What it does
- AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications.checked 1 Oct 2026
Money
- Billing
- Pay-as-you-go billing has no minimum commitments, upfront fees, contracts, or monthly subscription requirement, and invoices are generated monthly for prior usage.checked 1 Oct 2026
- Free plan
- Nochecked 20 Sep 2026
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