Kalpa Labs website screenshot

Kalpa Labs

Kalpa Labs is a San Francisco audio-research lab (Y Combinator Fall 2025) building generalist speech models that unify text-to-speech, multi-speaker conversation, voice cloning, and speech-in / speech-out reasoning behind one API — steerable with natural instructions and in-context learning the way a large language model is. Their Kalpa Speech API exposes stable public model ids over a clean REST interface: POST /v1/tts turns text into 24 kHz WAV audio, POST /v1/converse completes the open turn of a conversation (authored speech or contextual TTS), and a stateful WebSocket streams multi-speaker sessions. The developer surface ships a committed OpenAPI 3.1 contract, an AsyncAPI 3.0 WebSocket protocol, docs with a markdown twin per page, an llms.txt, and a browser Studio playground. Founded by Prashant Shishodia and Gautam Jha.

Kalpa Labs publishes 3 APIs on the APIs.io network: Meta API, Speech API, and Usage API. Tagged areas include Company, Speech, Text-to-Speech, Voice, and Audio.

Kalpa Labs’ developer surface includes documentation, API reference, getting-started guide, sandbox, support, authentication, and 17 more developer resources.

🌐 Visit website 📡 Source on GitHub
35.3/100 thin ▬ flat Agent 25/100 agent aware Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0
1 APIs
CompanySpeechText-to-SpeechVoiceAudioConversational AIMachine-LearningArtificial Intelligence

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0
Composite quality — 35.3/100 · thin
Contract Quality 12.0 / 23
Developer Ergonomics 12.7 / 18
Access Clarity 0.0 / 18
Operational Transparency 0.3 / 12
Contract Governance 0.5 / 11
Discoverability 6.8 / 9
Create-or-Update Ergonomics 0.0 / 10
Agent readiness — 25/100 · 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 0 / 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
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.
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/kalpa-labs: 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 3

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

Kalpa Labs Meta API

Health checks and capability discovery.

Kalpa Labs Speech API

Text-to-speech and conversational generation.

Kalpa Labs Usage API

Per-key usage and metering.

Open Collections 4

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

API Collection

OPEN COLLECTION

Kalpa Speech Meta API

OPEN COLLECTION

Kalpa Meta Speech API

OPEN COLLECTION

Kalpa Speech Meta Usage API

OPEN COLLECTION

Rate Limits 1

Documented rate limits and quota policies.

Kalpa Labs Rate Limits

0 limits

RATE LIMITS

Security Posture 2

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

Kalpa Labs Authentication

apiKey · 1 scheme

SECURITY

Kalpa Labs Domain Security

TLSv1.3 · DMARC

SECURITY

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 Sandbox
Sandbox

Documentation 3

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference
 AsyncAPI
AsyncAPI

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

X-MCPServerCandidate
X-MCPServerCandidate
 LLMsTxt
LLMsTxt
 AgentSkill
AgentSkill

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

ErrorCatalog
ErrorCatalog
 Conventions
Conventions
 Lifecycle
Lifecycle
 Conformance
Conformance
 DataModel
DataModel

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 Packages
Packages
 SDKs
SDKs

Access & Security 2

Authentication, authorization, and security posture

Authentication
Authentication
 DomainSecurity
DomainSecurity

Operate 2

Status, limits, changes, and where to get help

Support
Support
 RateLimits
RateLimits

Company 1

The organization behind the API

Website
Website

Other 1

Properties that don't map to a standard resource type

Overlay
Overlay

Source (apis.yml)

apis.yml Raw ↑ 
aid: kalpa-labs
name: Kalpa Labs
description: 'Kalpa Labs is a San Francisco audio-research lab (Y Combinator Fall 2025) building generalist speech models
  that unify text-to-speech, multi-speaker conversation, voice cloning, and speech-in / speech-out reasoning behind one API
  — steerable with natural instructions and in-context learning the way a large language model is. Their Kalpa Speech API
  exposes stable public model ids over a clean REST interface: POST /v1/tts turns text into 24 kHz WAV audio, POST /v1/converse
  completes the open turn of a conversation (authored speech or contextual TTS), and a stateful WebSocket streams multi-speaker
  sessions. The developer surface ships a committed OpenAPI 3.1 contract, an AsyncAPI 3.0 WebSocket protocol, docs with a
  markdown twin per page, an llms.txt, and a browser Studio playground. Founded by Prashant Shishodia and Gautam Jha.'
url: https://raw.githubusercontent.com/api-evangelist/kalpa-labs/refs/heads/main/apis.yml
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: true
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - rate-limits
  - security
  generated: '2026-09-03'
  method: derived
image: https://kalpalabs.ai/og.png
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
- nexus-venture-partners
- n1
x-tier: active
x-tier-reason: enriched
x-location: San Francisco, CA
x-yc-batch: F25
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Speech
- Text-to-Speech
- Voice
- Audio
- Conversational AI
- Machine-Learning
- Artificial Intelligence
tags_raw:
- Company
- Speech
- Text to Speech
- Voice
- Audio
- Conversational AI
- Machine Learning
- Artificial Intelligence
apis:
- aid: kalpa-labs:kalpa-labs-meta-api
  name: Kalpa Labs Meta API
  description: Health checks and capability discovery.
  humanURL: https://docs.kalpalabs.ai
  baseURL: https://api.kalpalabs.ai
  tags:
  - Meta
  properties:
  - type: OpenAPI
    url: openapi/kalpa-labs-meta-api-openapi.yml
  - type: AsyncAPI
    url: asyncapi/kalpa-labs-converse-stream-asyncapi.json
- aid: kalpa-labs:kalpa-labs-speech-api
  name: Kalpa Labs Speech API
  description: Text-to-speech and conversational generation.
  humanURL: https://docs.kalpalabs.ai
  baseURL: https://api.kalpalabs.ai
  tags:
  - Speech
  properties:
  - type: OpenAPI
    url: openapi/kalpa-labs-speech-api-openapi.yml
  - type: AsyncAPI
    url: asyncapi/kalpa-labs-converse-stream-asyncapi.json
- aid: kalpa-labs:kalpa-labs-usage-api
  name: Kalpa Labs Usage API
  description: Per-key usage and metering.
  humanURL: https://docs.kalpalabs.ai
  baseURL: https://api.kalpalabs.ai
  tags:
  - Usage
  properties:
  - type: OpenAPI
    url: openapi/kalpa-labs-usage-api-openapi.yml
  - type: AsyncAPI
    url: asyncapi/kalpa-labs-converse-stream-asyncapi.json
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://kalpalabs.ai
- type: DeveloperPortal
  url: https://docs.kalpalabs.ai
- type: Documentation
  url: https://docs.kalpalabs.ai
- type: APIReference
  url: https://docs.kalpalabs.ai/reference
- type: GettingStarted
  url: https://docs.kalpalabs.ai/quickstart
- type: Sandbox
  url: https://studio.kalpalabs.ai
- type: GitHubOrganization
  url: https://github.com/kalpalabs
- type: Support
  url: mailto:hello@kalpalabs.ai
- type: Authentication
  url: authentication/kalpa-labs-authentication.yml
- type: DomainSecurity
  url: security/kalpa-labs-domain-security.yml
- type: ErrorCatalog
  url: errors/kalpa-labs-problem-types.yml
- type: Conventions
  url: conventions/kalpa-labs-conventions.yml
- type: RateLimits
  url: rate-limits/kalpa-labs-rate-limits.yml
- type: Lifecycle
  url: lifecycle/kalpa-labs-lifecycle.yml
- type: X-MCPServerCandidate
  url: mcp/kalpa-labs-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: LLMsTxt
  url: llms/kalpa-labs-llms.txt
- type: Overlay
  url: overlays/kalpa-labs-openapi-overlay.yaml
- type: Conformance
  url: conformance/kalpa-labs-conformance.yml
- type: DataModel
  url: data-model/kalpa-labs-data-model.yml
- type: Packages
  url: packages/kalpa-labs-packages.yml
- type: SDKs
  url: packages/kalpa-labs-packages.yml
- type: AsyncAPI
  url: asyncapi/kalpa-labs-converse-stream-asyncapi.json
- type: AgentSkill
  url: skills/_index.yml
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence

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