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
33.7/100 thin ▬ flat Agent 25/100 agent aware Front door AI 1/6 silent Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0
1 APIs
CompanySpeechText-to-SpeechVoiceAudioConversational AIMachine LearningArtificial IntelligenceReal-Time

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0
Composite quality — 33.7/100 · thin
Contract Quality 9.0 / 19
Developer Ergonomics 10.6 / 15
Access Clarity 0.0 / 15
Operational Transparency 0.3 / 10
Contract Governance 0.4 / 9
Discoverability 5.5 / 8
Regulatory Posture 2.3 / 15
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
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/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
- Real-Time
tags_raw:
- Company
- Speech
- Text to Speech
- Voice
- Audio
- Conversational AI
- Machine Learning
- Artificial Intelligence
- Machine-Learning
- Real-Time
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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