LMNT website screenshot

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 3 APIs on the APIs.io network: Ai API, Health Check API, and Speech API. 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
49.1/100 developing ▬ flat Agent 38/100 agent ready Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessFreemiumSelf serve⚡ Free to try
4 APIs
text-to-speechvoice synthesisvoice cloningaudio streamingconversational AIlow latencyreal-time audio

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 49.1/100 · developing
Contract Quality 15.2 / 25
Developer Ergonomics 3.9 / 20
Commercial Clarity 11.6 / 20
Operational Transparency 2.7 / 13
Governance 8.3 / 12
Discoverability 7.4 / 10
Agent readiness — 38/100 · agent ready
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
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
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. 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. Want it done for you? Prioritized profiling — $2,500 →

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.

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

0 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

14 operations · 8 acting

AGENTIC

Resources

Documentation 4

Reference material describing how the API behaves

Documentation
Documentation
 OpenAPI
OpenAPI
 JSONSchema
JSONSchema
 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
LinkedIn

Other 1

Properties that don't map to a standard resource type

X
X

Source (apis.yml)

apis.yml Raw ↑ 
aid: lmnt
name: LMNT
type: Index
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  label: Freemium · Self-serve signup
  confidence: high
  source:
  - plans
  - authentication
  generated: '2026-07-22'
  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: '0.19'
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
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
  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:
  - 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/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