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
48.6/100 developing ▬ flat Agent 26/100 agent aware saas Full breakdown ↓
scored 2026-09-06 · rubric v0.19.0
1 APIs
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 2026-09-06 · rubric v0.19.0
Composite quality — 48.6/100 · developing
Contract Quality 14.1 / 25
Developer Ergonomics 15.6 / 20
Access Clarity 6.3 / 20
Operational Transparency 4.4 / 13
Contract Governance 0.5 / 12
Discoverability 7.6 / 10
Agent readiness — 26/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 0 / 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 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
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/gradium: 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 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

Open Collections 7

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

API Collection

OPEN COLLECTION

Gradium metering API

OPEN COLLECTION

Gradium metering Pronunciations API

OPEN COLLECTION

Gradium metering S2S API

OPEN COLLECTION

Gradium metering STT API

OPEN COLLECTION

Gradium metering TTS API

OPEN COLLECTION

Gradium metering Voices API

OPEN COLLECTION

Scroll for all 7

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
 X-MCPServerCandidate
X-MCPServerCandidate
 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.
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: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-09-03'
  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: '0.23'
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
tags_raw:
- 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
  tags_raw:
  - 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/_original/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: X-MCPServerCandidate
  url: mcp/gradium-mcp.yml
  note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list derived
    from the published API contracts, not an existing server. The scorer already read the manifest and reported mcp_server
    correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
- 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

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/gradium"
All providers 
curl "https://apis.io/api/v1/providers?limit=25"
Every operation they expose 
curl "https://apis.io/api/v1/providers/gradium/operations?limit=25"
How their score was established 
curl "https://apis.io/api/v1/providers/gradium/evidence"

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

Get an API key

Free tier, no email required.

GitHub Google LinkedIn

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