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 APIs 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 📡 Source on GitHub

43.1/100 developing ▬ flat Agent 26/100 agent aware saas Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0

AccessFreemiumSelf serve⚡ Free to try

1 APIs

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

Kin Score

Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0

Composite quality — 43.1/100 · developing

Contract Quality 10.0 / 19

Developer Ergonomics 3.2 / 15

Access Clarity 8.2 / 15

Operational Transparency 3.6 / 10

Contract Governance 2.1 / 9

Discoverability 5.0 / 8

Regulatory Posture 3.2 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 26/100 · 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

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) 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/.

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 github.com/api-evangelist/lmnt: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

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 4

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

API Collection

OPEN COLLECTION

LMNT Speech Ai API

OPEN COLLECTION

LMNT Speech Ai Health Check API

OPEN COLLECTION

LMNT Ai Speech API

OPEN COLLECTION

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

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 API 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
  label: Freemium · Self-serve signup
  confidence: medium
  source:
  - plans
  - authentication
  - security
  generated: '2026-09-03'
  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

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for providers

9 MCP tools reach this

find_providersBrowse and filter every provider in the catalog.
get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

This provider

curl "https://apis.io/api/v1/providers/lmnt"

All providers

curl "https://apis.io/api/v1/providers?limit=25"

Every operation they expose

curl "https://apis.io/api/v1/providers/lmnt/operations?limit=25"

How their score was established

curl "https://apis.io/api/v1/providers/lmnt/evidence"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.