AssemblyAI

Built by AI experts, AssemblyAI's Speech AI models include accurate speech-to-text for voice data (such as calls, virtual meetings, and podcasts), speaker detection, sentiment analysis, chapter detection, PII redaction, and more. AssemblyAI provides powerful APIs for transcribing and understanding audio data at scale. The platform supports real-time streaming transcription via WebSocket, asynchronous batch transcription, and audio intelligence features including summarization, auto chapters, entity detection, and content safety filtering. SDKs are available for Python, Node.js, Ruby, Java, and Go.

AssemblyAI publishes 3 API contracts indexed on the APIs.io network: LeMUR API, Streaming API, and Transcript API. Tagged areas include Artificial Intelligence, Audio, Speech, Transcription, and Speech-to-Text.

The AssemblyAI catalog on APIs.io includes 1 event-driven AsyncAPI specification and 1 Spectral governance ruleset.

AssemblyAI’s developer surface includes developer portal, documentation, engineering blog, signup flow, pricing, and 13 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

45.9/100 developing ▬ flat Agent 30/100 agent ready Front door AI 6/6 dominant Heartbeat 96/100 alive saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessPaid

2 published contracts 1 Agent Skills 5 Features 5 Use Cases

Artificial Intelligence Audio Speech Transcription Speech-to-Text Voice Real-Time Voice AI

What this lets a business do 1

Business capabilities this provider's published APIs can perform, derived from its own contracts. Browse all capabilities →

AI Model Services

AE-110

Transcript

POST /v2/transcript GET /v2/transcript GET /v2/transcript/{transcript_id} GET /v2/transcript/{transcript_id}/{subtitle_format}

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 45.9/100 · developing

Contract Quality 9.9 / 19

Developer Ergonomics 7.0 / 15

Access Clarity 9.7 / 15

Operational Transparency 2.6 / 10

Contract Governance 1.0 / 9

Discoverability 5.0 / 8

Regulatory Posture 2.3 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 30/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the AI & Biometrics regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)

6 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 53.0 — up to +11.8 composite points
Developer Ergonomics scores 46.9 — up to +10.6 composite points
Contract Governance scores 11.4 — up to +10.6 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/assemblyai/apis.yml: open an issue on github.com/api-evangelist/assemblyai to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Retrieval, Vector and RAG	covered	31.8	-	1
Speech and Voice AI	covered	31.8	-	1
Agent Skills (SKILL.md packages)	covered	31.8	-	1
Obsidian Community Plugins (third-party APIs the Obsidian plugin ecosystem integrates)	covered	31.8	-	1
IFTTT Services (service publishers)	covered	31.8	-	1
Hugging Face Hub Organisations	covered	31.8	-	1

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

OpenAPI

measured — observed by APIs.io (published)

APIs 3

Individual APIs this provider publishes, each with its own machine-readable definition.

AssemblyAI LeMUR API

LeMUR related operations

AssemblyAI Streaming API

Streaming Speech-to-Text

AssemblyAI Transcript API

Transcript related operations

Open Collections 3

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

AssemblyAI LeMUR API

OPEN COLLECTION

AssemblyAI LeMUR Streaming API

OPEN COLLECTION

AssemblyAI LeMUR Transcript API

OPEN COLLECTION

Agent Skills 1

Packaged agent skills for driving this provider's APIs from an AI assistant.

assemblyai

AGENT SKILL

AssemblyAI API pricing

Prices published by AssemblyAI, read 2026-10-07 from www.assemblyai.com/pricing.

Plan	Price
Universal-3.5 Pro (pre-recorded)	$0.21/hr
Universal-2 (pre-recorded)	$0.15/hr
Universal-3.6 Pro Realtime	$0.45/hr
Sync API	$0.30/hr Includes: Keyterms Prompting and Conversation Context included
Voice Agent API	$4.50/hr ($0.075/min) Includes: All features included; billed per second
Dictation API	$0.62/hr Includes: Keyterms Prompting, Prompting, Output Instruction included
Custom / Enterprise	Contact us Includes: Custom rate limits, enhanced concurrency
GPT-5 Nano (LLM Gateway)	$0.05/ 1M

All 9 plans, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against AssemblyAI's documentation. All 5 limits →

Billed by: hour of audio · FinOps profile →

Pricing Plans 1

Published pricing tiers and plan structures.

Assemblyai Plans Pricing

9 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Assemblyai Rate Limits

5 limits

RATE LIMITS

Service Levels 1

Uptime the provider promises or reports, as SLA4OAI. Read from its own pages; APIs.io runs no monitors.

AssemblyAI

SLA

FinOps 1

Cost, billing, and metering signals for API financial operations.

Assemblyai Finops

FINOPS

Features 5

Notable capabilities this provider offers.

Speech-to-Text Transcription

High-accuracy transcription of audio files and streams using AssemblyAI's Universal-2 model with support for 99+ languages and custom vocabulary.

Real-Time Streaming Transcription

WebSocket-based streaming transcription for live audio with partial results and final transcripts, supporting call centers, live captioning, and voice applications.

Speaker Diarization

Automatic speaker detection and labeling that identifies who said what in multi-speaker recordings.

Audio Intelligence

Advanced understanding features including sentiment analysis, summarization, auto chapters, entity detection, content safety filtering, and PII redaction.

LeMUR

LeMUR (Leveraging Large Language Models for Understanding Recordings) enables asking questions of audio transcripts using a conversational AI interface built on top of transcrip...

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

AssemblyAI Universal Streaming Speech-to-Text API

AsyncAPI specification for the AssemblyAI Universal Streaming Speech-to-Text WebSocket API (v3). Clients open a WebSocket to `wss://streaming.assemblyai.com/v3/ws`, send raw bin...

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

AssemblyAI — asyncapi rules

5 rules · 5 warnings

SPECTRAL

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Assemblyai Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Assemblyai Trust Center

SOC 2, PCI DSS, GDPR

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Assemblyai Agentic Access

16 operations · 9 acting

AGENTIC

Use Cases 5

What developers build with this provider.

Call Center Analytics

Customer service teams transcribe and analyze customer calls for quality assurance, compliance, agent coaching, and sentiment analysis.

Meeting Intelligence

Enterprises transcribe virtual meetings (Zoom, Teams, Meet) to generate summaries, action items, and searchable archives.

Podcast Processing

Podcast producers transcribe episodes for SEO, accessibility, show notes, and content repurposing.

Voice Application Development

Developers build voice-powered applications using real-time streaming transcription for voice commands, dictation, and conversation interfaces.

Compliance and Legal

Legal and compliance teams transcribe depositions, hearings, and recorded communications with PII redaction and timestamped transcripts.

Integrations 4

Pre-built integrations with other platforms and tools.

Twilio

Integration with Twilio Media Streams for transcribing phone calls in real-time using AssemblyAI's streaming API.

Zoom

Integration with Zoom recordings for batch transcription and meeting intelligence processing.

Python SDK

Official Python SDK for AssemblyAI available on PyPI (assemblyai) for easy integration in Python applications.

Node.js SDK

Official Node.js SDK for AssemblyAI available on npm (@assemblyai/sdk) for JavaScript and TypeScript applications.

Resources

Get Started 3

Portal, sign-up, and the first successful call

AssemblyAI Website

Portal

Sign Up

Signup

Login

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

AgentSkills

AgentSkills

Build 1

SDKs, sample code, and the tooling you integrate with

AssemblyAI GitHub Organization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

TrustCenter

TrustCenter

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

RateLimits

RateLimits

Status Page

StatusPage

Commercial 3

Pricing, plans, and the legal terms of use

FinOps

FinOps

Plans

Plans

Pricing

Pricing

Company 3

The organization behind the API

Website

Website

LinkedIn

Blog

Blog

Other 1

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Source (apis.yml)

aid: assemblyai
name: AssemblyAI
description: Built by AI experts, AssemblyAI's Speech AI models include accurate speech-to-text for voice data (such as calls,
  virtual meetings, and podcasts), speaker detection, sentiment analysis, chapter detection, PII redaction, and more. AssemblyAI
  provides powerful APIs for transcribing and understanding audio data at scale. The platform supports real-time streaming
  transcription via WebSocket, asynchronous batch transcription, and audio intelligence features including summarization,
  auto chapters, entity detection, and content safety filtering. SDKs are available for Python, Node.js, Ruby, Java, and Go.
type: Index
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: paid
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Paid
  confidence: low
  source:
  - plans
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/assemblyai.png
tags:
- Artificial Intelligence
- Audio
- Speech
- Transcription
- Speech-to-Text
- Voice
- Real-Time
- Voice AI
tags_raw:
- AI
- Artificial Intelligence
- Audio
- Speech
- Transcription
- Speech to Text
- Voice
- Real-Time
- Voice AI
url: https://raw.githubusercontent.com/api-evangelist/assemblyai/refs/heads/main/apis.yml
created: '2024-06-06'
modified: '2026-05-19'
specificationVersion: '0.23'
apis:
- aid: assemblyai:assemblyai-lemur-api
  name: AssemblyAI LeMUR API
  description: LeMUR related operations
  humanURL: https://www.assemblyai.com/docs/
  baseURL: https://api.assemblyai.com
  tags:
  - LEMUR
  tags_raw:
  - LeMUR
  properties:
  - type: OpenAPI
    url: openapi/assemblyai-lemur-api-openapi.yml
  - type: Documentation
    url: https://www.assemblyai.com/docs/
  - type: GettingStarted
    url: https://www.assemblyai.com/docs/getting-started/transcribe-an-audio-file
  - type: Authentication
    url: https://www.assemblyai.com/docs/concepts/authentication
  - type: APIReference
    url: https://www.assemblyai.com/docs/api-reference/overview
  - type: AsyncAPI
    url: openapi/assemblyai-asyncapi-original.yml
  - type: AsyncAPI
    url: asyncapi/assemblyai-asyncapi.yml
- aid: assemblyai:assemblyai-streaming-api
  name: AssemblyAI Streaming API
  description: Streaming Speech-to-Text
  humanURL: https://www.assemblyai.com/docs/
  baseURL: https://api.assemblyai.com
  tags:
  - Streaming
  properties:
  - type: OpenAPI
    url: openapi/assemblyai-streaming-api-openapi.yml
  - type: Documentation
    url: https://www.assemblyai.com/docs/
  - type: GettingStarted
    url: https://www.assemblyai.com/docs/getting-started/transcribe-an-audio-file
  - type: Authentication
    url: https://www.assemblyai.com/docs/concepts/authentication
  - type: APIReference
    url: https://www.assemblyai.com/docs/api-reference/overview
  - type: AsyncAPI
    url: openapi/assemblyai-asyncapi-original.yml
  - type: AsyncAPI
    url: asyncapi/assemblyai-asyncapi.yml
- aid: assemblyai:assemblyai-transcript-api
  name: AssemblyAI Transcript API
  description: Transcript related operations
  humanURL: https://www.assemblyai.com/docs/
  baseURL: https://api.assemblyai.com
  tags:
  - Transcript
  tags_raw:
  - Transcript
  properties:
  - type: OpenAPI
    url: openapi/assemblyai-transcript-api-openapi.yml
  - type: Documentation
    url: https://www.assemblyai.com/docs/
  - type: GettingStarted
    url: https://www.assemblyai.com/docs/getting-started/transcribe-an-audio-file
  - type: Authentication
    url: https://www.assemblyai.com/docs/concepts/authentication
  - type: APIReference
    url: https://www.assemblyai.com/docs/api-reference/overview
  - type: AsyncAPI
    url: openapi/assemblyai-asyncapi-original.yml
  - type: AsyncAPI
    url: asyncapi/assemblyai-asyncapi.yml
common:
- type: CapabilityMap
  url: capabilities/assemblyai-capability-edges.yml
  name: AssemblyAI Business Capability Map
- type: RateLimits
  url: rate-limits/assemblyai-rate-limits.yml
- type: FinOps
  url: finops/assemblyai-finops.yml
- type: Plans
  url: plans/assemblyai-plans-pricing.yml
- type: Website
  url: https://www.assemblyai.com/
- type: AgenticAccess
  url: agentic-access/assemblyai-agentic-access.yml
- type: TrustCenter
  url: security/assemblyai-trust-center.yml
- type: DomainSecurity
  url: security/assemblyai-domain-security.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/assemblyai
- type: Portal
  url: https://www.assemblyai.com/
  title: AssemblyAI Website
- type: Documentation
  url: https://www.assemblyai.com/docs/
  title: Documentation
- type: Blog
  url: https://www.assemblyai.com/blog
  title: Blog
- type: Signup
  url: https://www.assemblyai.com/dashboard/signup
  title: Sign Up
- type: Login
  url: https://www.assemblyai.com/dashboard/login
  title: Login
- type: Pricing
  url: https://www.assemblyai.com/pricing
  title: Pricing
- type: GitHubOrganization
  url: https://github.com/AssemblyAI
  title: AssemblyAI GitHub Organization
- type: StatusPage
  url: https://status.assemblyai.com/
  title: Status Page
- type: Features
  data:
  - name: Speech-to-Text Transcription
    description: High-accuracy transcription of audio files and streams using AssemblyAI's Universal-2 model with support
      for 99+ languages and custom vocabulary.
  - name: Real-Time Streaming Transcription
    description: WebSocket-based streaming transcription for live audio with partial results and final transcripts, supporting
      call centers, live captioning, and voice applications.
  - name: Speaker Diarization
    description: Automatic speaker detection and labeling that identifies who said what in multi-speaker recordings.
  - name: Audio Intelligence
    description: Advanced understanding features including sentiment analysis, summarization, auto chapters, entity detection,
      content safety filtering, and PII redaction.
  - name: LeMUR
    description: LeMUR (Leveraging Large Language Models for Understanding Recordings) enables asking questions of audio transcripts
      using a conversational AI interface built on top of transcriptions.
- type: UseCases
  data:
  - name: Call Center Analytics
    description: Customer service teams transcribe and analyze customer calls for quality assurance, compliance, agent coaching,
      and sentiment analysis.
  - name: Meeting Intelligence
    description: Enterprises transcribe virtual meetings (Zoom, Teams, Meet) to generate summaries, action items, and searchable
      archives.
  - name: Podcast Processing
    description: Podcast producers transcribe episodes for SEO, accessibility, show notes, and content repurposing.
  - name: Voice Application Development
    description: Developers build voice-powered applications using real-time streaming transcription for voice commands, dictation,
      and conversation interfaces.
  - name: Compliance and Legal
    description: Legal and compliance teams transcribe depositions, hearings, and recorded communications with PII redaction
      and timestamped transcripts.
- type: Integrations
  data:
  - name: Twilio
    description: Integration with Twilio Media Streams for transcribing phone calls in real-time using AssemblyAI's streaming
      API.
  - name: Zoom
    description: Integration with Zoom recordings for batch transcription and meeting intelligence processing.
  - name: Python SDK
    description: Official Python SDK for AssemblyAI available on PyPI (assemblyai) for easy integration in Python applications.
  - name: Node.js SDK
    description: Official Node.js SDK for AssemblyAI available on npm (@assemblyai/sdk) for JavaScript and TypeScript applications.
- name: Agent Skills
  url: https://github.com/AssemblyAI/assemblyai-skill
  type: AgentSkills
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

AssemblyAI API — frequently asked questions

Does AssemblyAI have an API?

Yes. APIs.io lists 3 APIs from AssemblyAI, including AssemblyAI LeMUR API, AssemblyAI Streaming API and AssemblyAI Transcript API.

Is there an OpenAPI specification for the AssemblyAI API?

Yes. APIs.io indexes 3 OpenAPI specifications for AssemblyAI, each linked for download from this page.

How do I authenticate with the AssemblyAI API?

AssemblyAI uses bearer-token authentication.

How much does the AssemblyAI API cost?

AssemblyAI publishes its prices; its Universal-3.5 Pro (pre-recorded) plan is $0.21/hr as of 2026-10-07. APIs.io lists 9 pricing plans for AssemblyAI, with each plan's price, limits and inclusions under Pricing on this page.

Is the AssemblyAI API ready for AI agents?

AssemblyAI has a Kin Score of 45.9 out of 100 (developing) and an Agent Readiness score of 29.5 (agent-ready), scored by API Evangelist on 2026-11-06.

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