Gradium website screenshot

Gradium

Gradium is a voice AI lab (Paris and Silicon Valley) building audio language models for real-time, low-latency Text-to-Speech, Speech-to-Text, and Speech-to-Speech translation. Founded in 2025 by ex-DeepMind / Meta / Kyutai researchers (Neil Zeghidour, Olivier Teboul, Laurent Mazaré, Alexandre Défossez), Gradium exposes a developer API over REST and WebSocket featuring instant voice cloning from a 10-second sample, custom pronunciation dictionaries, sub-300ms time-to-first-token streaming, and multilingual support (English, French, German, Spanish, Portuguese). It ships first-party Python and Rust SDKs, a `gradium` CLI, and the open-source gradbot voice-agent framework, and is available on AWS Marketplace / SageMaker. Backed by a $70M seed round with participation from Amplify Partners, Eric Schmidt, and Xavier Niel.

Gradium publishes 6 APIs on the APIs.io network, including metering API, Pronunciations API, S2S API, and 3 more. Tagged areas include Company, Ai Ml, Voice AI, Text-to-Speech, and Speech-to-Text.

The Gradium catalog on APIs.io includes 1 event-driven AsyncAPI specification.

Gradium’s developer surface includes documentation, API reference, getting-started guide, CLI, authentication, changelog, sandbox, and 29 more developer resources.

🌐 Visit website 📡 Source on GitHub
57.4/100 developing ▬ flat Agent 64/100 agent native Full breakdown ↓
scored 2026-07-27 · rubric v0.5
AccessSelf serve
6 APIs 1 MCP Servers
CompanyAi MlVoice AIText-to-SpeechSpeech-to-TextSpeech-to-SpeechVoice CloningAudioReal-Time StreamingWebSocketDeveloper APIVoice Agents

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 57.4/100 · developing
Contract Quality 13.7 / 25
Developer Ergonomics 17.4 / 20
Commercial Clarity 10.5 / 20
Operational Transparency 5.8 / 13
Governance 0.0 / 12
Discoverability 10.0 / 10
Agent readiness — 64/100 · agent native
Machine-Readable Contract 18 / 18
Agentic Access Contract 0 / 15
MCP Server 12 / 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 6 / 6
Agent Skills 5 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
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/gradium: 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 6

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

Gradium metering API

The metering API from Gradium — 1 operation(s) for metering.

Gradium Pronunciations API

Manage pronunciation dictionaries for custom text rewriting

Gradium S2S API

The S2S API from Gradium — 1 operation(s) for s2s.

Gradium STT API

Speech-to-Text endpoints for converting audio to text

Gradium TTS API

Text-to-Speech endpoints for converting text to audio

Gradium Voices API

Manage custom voice clones

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

gradium-mcp.yml

MCP SERVER

Event Specifications 1

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

Gradium Speech Streaming API

AsyncAPI capture of Gradium's real-time speech WebSocket surface (TTS, STT, and Speech-to-Speech). Generated by API Evangelist from the documented WebSocket lifecycle and messag...

ASYNCAPI

Security Posture 2

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

Gradium Authentication

apiKey/bearer-token · 2 schemes

SECURITY

Gradium Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Get Started 5

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 Sandbox
Sandbox
 SignUp
SignUp
 Login
Login

Documentation 4

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference
 OpenAPI
OpenAPI
 AsyncAPI
AsyncAPI

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt
LLMsTxt
 MCPServer
MCPServer
 AgentSkill
AgentSkill

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions
Conventions
 ErrorCatalog
ErrorCatalog
 Conformance
Conformance
 DataModel
DataModel
 Lifecycle
Lifecycle

Build 4

SDKs, sample code, and the tooling you integrate with

SDKs
SDKs
 Packages
Packages
 CLI
CLI
 GitHubOrganization
GitHubOrganization

Access & Security 3

Authentication, authorization, and security posture

Authentication
Authentication
 DomainSecurity
DomainSecurity
 TrustCenter
TrustCenter

Operate 6

Status, limits, changes, and where to get help

Deprecation
Deprecation
 ChangeLog
ChangeLog
 RateLimits
RateLimits
 StatusPage
StatusPage
 Support
Support
 Community
Community

Commercial 3

Pricing, plans, and the legal terms of use

Pricing
Pricing
 TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy

Company 2

The organization behind the API

Website
Website
 Blog
Blog

Other 1

Properties that don't map to a standard resource type

Overlay
Overlay

Source (apis.yml)

apis.yml Raw ↑ 
aid: gradium
name: Gradium
description: Gradium is a voice AI lab (Paris and Silicon Valley) building audio language models for real-time, low-latency
  Text-to-Speech, Speech-to-Text, and Speech-to-Speech translation. Founded in 2025 by ex-DeepMind / Meta / Kyutai researchers
  (Neil Zeghidour, Olivier Teboul, Laurent Mazaré, Alexandre Défossez), Gradium exposes a developer API over REST and WebSocket
  featuring instant voice cloning from a 10-second sample, custom pronunciation dictionaries, sub-300ms time-to-first-token
  streaming, and multilingual support (English, French, German, Spanish, Portuguese). It ships first-party Python and Rust
  SDKs, a `gradium` CLI, and the open-source gradbot voice-agent framework, and is available on AWS Marketplace / SageMaker.
  Backed by a $70M seed round with participation from Amplify Partners, Eric Schmidt, and Xavier Niel.
accessModel:
  pricing: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://gradium.ai/assets/dots_1200.png
url: https://raw.githubusercontent.com/api-evangelist/gradium/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- amplify-partners
x-tier: enriched
x-tier-reason: portfolio-lead
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Ai Ml
- Voice AI
- Text-to-Speech
- Speech-to-Text
- Speech-to-Speech
- Voice Cloning
- Audio
- Real-Time Streaming
- WebSocket
- Developer API
- Voice Agents
apis:
- aid: gradium:gradium-metering-api
  name: Gradium metering API
  description: The metering API from Gradium — 1 operation(s) for metering.
  humanURL: https://docs.gradium.ai/api-reference/introduction
  baseURL: https://api.gradium.ai/api
  tags:
  - metering
  properties:
  - type: OpenAPI
    url: openapi/gradium-metering-api-openapi.yml
  - type: Documentation
    url: https://docs.gradium.ai/
  - type: APIReference
    url: https://docs.gradium.ai/api-reference/introduction
  - type: Authentication
    url: authentication/gradium-authentication.yml
- aid: gradium:gradium-pronunciations-api
  name: Gradium Pronunciations API
  description: Manage pronunciation dictionaries for custom text rewriting
  humanURL: https://docs.gradium.ai/api-reference/introduction
  baseURL: https://api.gradium.ai/api
  tags:
  - Pronunciations
  properties:
  - type: OpenAPI
    url: openapi/gradium-pronunciations-api-openapi.yml
  - type: Documentation
    url: https://docs.gradium.ai/
  - type: APIReference
    url: https://docs.gradium.ai/api-reference/introduction
  - type: Authentication
    url: authentication/gradium-authentication.yml
- aid: gradium:gradium-s2s-api
  name: Gradium S2S API
  description: The S2S API from Gradium — 1 operation(s) for s2s.
  humanURL: https://docs.gradium.ai/api-reference/introduction
  baseURL: https://api.gradium.ai/api
  tags:
  - S2S
  properties:
  - type: OpenAPI
    url: openapi/gradium-s2s-api-openapi.yml
  - type: Documentation
    url: https://docs.gradium.ai/
  - type: APIReference
    url: https://docs.gradium.ai/api-reference/introduction
  - type: Authentication
    url: authentication/gradium-authentication.yml
- aid: gradium:gradium-stt-api
  name: Gradium STT API
  description: Speech-to-Text endpoints for converting audio to text
  humanURL: https://docs.gradium.ai/api-reference/introduction
  baseURL: https://api.gradium.ai/api
  tags:
  - STT
  properties:
  - type: OpenAPI
    url: openapi/gradium-stt-api-openapi.yml
  - type: Documentation
    url: https://docs.gradium.ai/
  - type: APIReference
    url: https://docs.gradium.ai/api-reference/introduction
  - type: Authentication
    url: authentication/gradium-authentication.yml
- aid: gradium:gradium-tts-api
  name: Gradium TTS API
  description: Text-to-Speech endpoints for converting text to audio
  humanURL: https://docs.gradium.ai/api-reference/introduction
  baseURL: https://api.gradium.ai/api
  tags:
  - TTS
  properties:
  - type: OpenAPI
    url: openapi/gradium-tts-api-openapi.yml
  - type: Documentation
    url: https://docs.gradium.ai/
  - type: APIReference
    url: https://docs.gradium.ai/api-reference/introduction
  - type: Authentication
    url: authentication/gradium-authentication.yml
- aid: gradium:gradium-voices-api
  name: Gradium Voices API
  description: Manage custom voice clones
  humanURL: https://docs.gradium.ai/api-reference/introduction
  baseURL: https://api.gradium.ai/api
  tags:
  - Voices
  properties:
  - type: OpenAPI
    url: openapi/gradium-voices-api-openapi.yml
  - type: Documentation
    url: https://docs.gradium.ai/
  - type: APIReference
    url: https://docs.gradium.ai/api-reference/introduction
  - type: Authentication
    url: authentication/gradium-authentication.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://gradium.ai
- type: DeveloperPortal
  url: https://docs.gradium.ai/
- type: Documentation
  url: https://docs.gradium.ai/
- type: APIReference
  url: https://docs.gradium.ai/api-reference/introduction
- type: GettingStarted
  url: https://docs.gradium.ai/guides/installation
- type: OpenAPI
  url: openapi/gradium-openapi-original.json
- type: LLMsTxt
  url: llms/gradium-llms.txt
- type: SDKs
  url: packages/gradium-packages.yml
- type: Packages
  url: packages/gradium-packages.yml
- type: CLI
  url: cli/gradium-cli.yml
- type: MCPServer
  url: mcp/gradium-mcp.yml
- type: Authentication
  url: authentication/gradium-authentication.yml
- type: Conventions
  url: conventions/gradium-conventions.yml
- type: ErrorCatalog
  url: errors/gradium-error-codes.yml
- type: Conformance
  url: conformance/gradium-conformance.yml
- type: DataModel
  url: data-model/gradium-data-model.yml
- type: Overlay
  url: overlays/gradium-openapi-overlay.yaml
- type: AsyncAPI
  url: asyncapi/gradium-speech-asyncapi.yml
- type: Lifecycle
  url: lifecycle/gradium-lifecycle.yml
- type: Deprecation
  url: lifecycle/gradium-lifecycle.yml
- type: ChangeLog
  url: changelog/gradium-changelog.yml
- type: DomainSecurity
  url: security/gradium-domain-security.yml
- type: AgentSkill
  url: skills/_index.yml
- type: RateLimits
  url: https://docs.gradium.ai/guides/limits
- type: StatusPage
  url: https://gradium.statuspage.io/
- type: TrustCenter
  url: https://trust.gradium.ai/
- type: Sandbox
  url: https://studio.gradium.ai/
- type: Blog
  url: https://gradium.ai/blog
- type: GitHubOrganization
  url: https://github.com/gradium-ai
- type: Support
  url: mailto:support@gradium.ai
- type: Community
  url: https://discord.com/invite/bcysuPRzXE
- type: Pricing
  url: https://gradium.ai/pricing
- type: SignUp
  url: https://studio.gradium.ai/platform/subscription
- type: Login
  url: https://accounts.gradium.ai/sign-in
- type: TermsOfService
  url: https://www.gradium.ai/terms-of-service
- type: PrivacyPolicy
  url: https://www.gradium.ai/privacy
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence