LMNT

LMNT is a text-to-speech API platform delivering ultra-low latency voice synthesis with streaming audio output designed for real-time conversational AI applications. The platform provides a Speech API for standard text-to-speech generation and a Speech Sessions API for WebSocket-based real-time streaming integrated with LLM pipelines, achieving latency under 300 milliseconds. LMNT supports 31 languages and offers voice cloning from as little as five seconds of audio, with its Blizzard 2 model optimized for accuracy, expressiveness, and pronunciation. Authentication uses API keys managed via the app dashboard, with SDKs available for Python, TypeScript, and Go.

LMNT publishes 4 API contracts indexed on the APIs.io network, including Ai API, Health Check API, Speech API, and 1 more. Tagged areas include Text-to-Speech, Voice Synthesis, Voice Cloning, Audio Streaming, and Conversational AI.

The LMNT catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

LMNT’s developer surface includes authentication, documentation, pricing, changelog, and 15 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

35.2/100 thin ▬ flat Agent 22/100 agent aware Heartbeat 32/100 slowing saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

1 published contract

Text-to-SpeechVoice SynthesisVoice CloningAudio StreamingConversational AI Low LatencyReal-Time Audio

Kin Score

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

Composite quality — 35.2/100 · thin

Contract Quality 10.0 / 19

Developer Ergonomics 3.2 / 15

Access Clarity 3.9 / 15

Operational Transparency 2.3 / 10

Contract Governance 2.1 / 9

Discoverability 5.0 / 8

Regulatory Posture 3.1 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 22/100 · agent aware

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 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 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 0 / 5

Distinct Operations 0 / 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)
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link
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)

10 more unmet checks in the Agent Readiness table above.

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

Developer Ergonomics scores 21.4 — up to +15.7 composite points
Access Clarity scores 26.3 — up to +14.7 composite points
Contract Quality scores 53.5 — up to +11.6 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/lmnt/apis.yml: open an issue on github.com/api-evangelist/lmnt 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
Speech and Voice AI	mixed	37.0	-	-

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 4

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

LMNT Speech Sessions API

WebSocket-based real-time speech generation API for streaming LLM text output to synthesized audio with reset-latency support for conversational AI applications requiring interr...

LMNT Ai API

The Ai API from LMNT — 8 operation(s) for ai.

LMNT Health Check API

The Health Check API from LMNT — 1 operation(s) for health check.

LMNT Speech API

The Speech API from LMNT — 2 operation(s) for speech.

Open Collections 3

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

LMNT Speech Ai API

OPEN COLLECTION

LMNT Speech Ai Health Check API

OPEN COLLECTION

LMNT Ai Speech API

OPEN COLLECTION

LMNT API pricing

Not yet checked against LMNT's own pricing page. Compiled by API Evangelist on 2026-06-12; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free free	—
Indie freemium	—
Pro paid	—
Premium paid	—
Enterprise enterprise	—

Plan details, limits and sources →

Pricing Plans 1

Published pricing tiers and plan structures.

Lmnt Plans Pricing

5 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Lmnt Rate Limits

2 limits

RATE LIMITS

Service Levels 1

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

LMNT

SLA

FinOps 1

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

Lmnt Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Lmnt Context

0 classes · 24 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

LMNT — jsonschema rules

5 rules · 4 warnings 1 info

SPECTRAL

JSON Schema 2

Standalone JSON Schema definitions for this provider's data models.

LMNT Speech Synthesis Request

11 properties

JSON SCHEMA

LMNT Voice

10 properties

JSON SCHEMA

Examples 2

Example request and response payloads for these APIs.

Lmnt Speech Synthesis Request

7 fields

EXAMPLE

Lmnt Voice List Response

1 fields

EXAMPLE

Security Posture 3

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

Lmnt Authentication

apiKey · 1 scheme

SECURITY

Lmnt Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Lmnt Trust Center

SOC 2

SECURITY

Agentic Access 1

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

Lmnt Agentic Access

14 operations · 8 acting

AGENTIC

Resources

Documentation 4

Reference material describing how the API behaves

Documentation

OpenAPI

JSONSchema

JSONSchema

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

JSONLDContext

JSONLDContext

Vocabulary

Vocabulary

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 3

Authentication, authorization, and security posture

TrustCenter

TrustCenter

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 2

Status, limits, changes, and where to get help

ChangeLog

ChangeLog

RateLimits

RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

Plans

Plans

FinOps

FinOps

Company 2

The organization behind the API

Website

Website

LinkedIn

Other 1

Properties that don't map to a standard resource type

Source (apis.yml)

aid: lmnt
name: LMNT
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: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  gated: none
  gated_source:
  - onboarding
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/lmnt.png
url: https://raw.githubusercontent.com/api-evangelist/lmnt/refs/heads/main/apis.yml
created: 2026-06-12
modified: 2026-06-12
specificationVersion: '0.23'
description: 'LMNT is a text-to-speech API platform delivering ultra-low latency voice synthesis with streaming audio output
  designed for real-time conversational AI applications. The platform provides a Speech API for standard text-to-speech generation
  and a Speech Sessions API for WebSocket-based real-time streaming integrated with LLM pipelines, achieving latency under
  300 milliseconds. LMNT supports 31 languages and offers voice cloning from as little as five seconds of audio, with its
  Blizzard 2 model optimized for accuracy, expressiveness, and pronunciation. Authentication uses API keys managed via the
  app dashboard, with SDKs available for Python, TypeScript, and Go.

  '
tags:
- Text-to-Speech
- Voice Synthesis
- Voice Cloning
- Audio Streaming
- Conversational AI
- Low Latency
- Real-Time Audio
tags_raw:
- text-to-speech
- voice synthesis
- voice cloning
- audio streaming
- conversational AI
- low latency
- real-time audio
apis:
- name: LMNT Speech Sessions API
  description: 'WebSocket-based real-time speech generation API for streaming LLM text output to synthesized audio with reset-latency
    support for conversational AI applications requiring interrupt handling.

    '
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://docs.lmnt.com/api-reference/speech/generate-speech-session
  baseURL: wss://api.lmnt.com
  tags:
  - speech sessions
  - WebSocket
  - Real-Time
  - Streaming
  tags_raw:
  - speech sessions
  - websocket
  - real-time
  - streaming
  properties:
  - type: Documentation
    url: https://docs.lmnt.com/api-reference/speech/generate-speech-session
- aid: lmnt:lmnt-ai-api
  name: LMNT Ai API
  description: The Ai API from LMNT — 8 operation(s) for ai.
  humanURL: https://docs.lmnt.com/api-reference/speech/synthesize-speech-bytes
  baseURL: https://api.lmnt.com
  tags:
  - Artificial Intelligence
  tags_raw:
  - Ai
  properties:
  - type: OpenAPI
    url: openapi/lmnt-ai-api-openapi.yml
  - type: Documentation
    url: https://docs.lmnt.com/api-reference/speech/synthesize-speech-bytes
- aid: lmnt:lmnt-health-check-api
  name: LMNT Health Check API
  description: The Health Check API from LMNT — 1 operation(s) for health check.
  humanURL: https://docs.lmnt.com/api-reference/speech/synthesize-speech-bytes
  baseURL: https://api.lmnt.com
  tags:
  - Health Check
  properties:
  - type: OpenAPI
    url: openapi/lmnt-health-check-api-openapi.yml
  - type: Documentation
    url: https://docs.lmnt.com/api-reference/speech/synthesize-speech-bytes
- aid: lmnt:lmnt-speech-api
  name: LMNT Speech API
  description: The Speech API from LMNT — 2 operation(s) for speech.
  humanURL: https://docs.lmnt.com/api-reference/speech/synthesize-speech-bytes
  baseURL: https://api.lmnt.com
  tags:
  - Speech
  properties:
  - type: OpenAPI
    url: openapi/lmnt-speech-api-openapi.yml
  - type: Documentation
    url: https://docs.lmnt.com/api-reference/speech/synthesize-speech-bytes
common:
- type: AgenticAccess
  url: agentic-access/lmnt-agentic-access.yml
- type: TrustCenter
  url: security/lmnt-trust-center.yml
- type: DomainSecurity
  url: security/lmnt-domain-security.yml
- type: Authentication
  url: authentication/lmnt-authentication.yml
- type: Website
  url: https://www.lmnt.com/
- type: Documentation
  url: https://docs.lmnt.com/
- type: GitHubOrganization
  url: https://github.com/lmnt-com
- type: LinkedIn
  url: https://www.linkedin.com/company/lmnt
- type: X
  url: https://x.com/lmnt_com
- type: Pricing
  url: https://www.lmnt.com/pricing
- type: ChangeLog
  url: https://docs.lmnt.com/changelog/overview
- type: Plans
  url: plans/lmnt-plans-pricing.yml
- type: RateLimits
  url: rate-limits/lmnt-rate-limits.yml
- type: FinOps
  url: finops/lmnt-finops.yml
- type: OpenAPI
  url: openapi/_original/lmnt-speech-openapi.yml
- type: JSONSchema
  url: json-schema/lmnt-voice-schema.json
- type: JSONSchema
  url: json-schema/lmnt-speech-synthesis-schema.json
- type: JSONLDContext
  url: json-ld/lmnt-context.jsonld
- type: Vocabulary
  url: vocabulary/lmnt-vocabulary.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

LMNT API — frequently asked questions

Does LMNT have an API?

Yes. APIs.io lists 4 APIs from LMNT, including LMNT Speech Sessions API, LMNT Ai API and LMNT Health Check API, and 1 more.

Is there an OpenAPI specification for the LMNT API?

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

How do I authenticate with the LMNT API?

LMNT uses bearer-token authentication (apiKey · 1 scheme). The details are profiled on APIs.io as Lmnt Authentication.

How much does the LMNT API cost?

APIs.io lists 5 pricing plans for LMNT, with each plan's price, limits and inclusions under Pricing on this page.

Is the LMNT API ready for AI agents?

LMNT has a Kin Score of 35.2 out of 100 (thin) and an Agent Readiness score of 22.4 (agent-aware), scored by API Evangelist on 2026-11-06.

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