Chert

Chert is iMessage infrastructure for reaching people at scale. Its Messaging API lets teams programmatically send, receive, route, and observe real iMessage conversations — blue-bubble threads from verified numbers with typing indicators, tapback reactions, reply context, multi-recipient group threads, SMS fallback, file attachments, rich-link previews, one-time location pins, and delivery receipts. Chert also ships native integrations for Salesforce, HubSpot, and Slack, plus webhook subscriptions and an event stream (message.received, reaction.added/removed) for real-time inbound replies. Auth is bearer token or HMAC-SHA256 request signing; writes support an idempotency_key. Chert is a Y Combinator (Spring 2026) company based in the San Francisco Bay Area.

Chert publishes 1 API on the APIs.io network. Tagged areas include Company, Messaging, iMessage, Communications, and Conversational.

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

Chert’s developer surface includes documentation, API reference, getting-started guide, signup flow, support, engineering blog, authentication, and 15 more developer resources.

🌐 Visit website 📡 Source on GitHub

34.5/100 thin ▬ flat Agent 26/100 agent aware saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

1 APIs

Company Messaging iMessage Communications Conversational Webhook CRM Integration

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 34.5/100 · thin

Contract Quality 10.4 / 25

Developer Ergonomics 11.0 / 20

Access Clarity 4.2 / 20

Operational Transparency 1.4 / 13

Contract Governance 0.0 / 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 9 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 6 / 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

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 could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

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/chert: 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 1

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

Chert Messaging API

Programmatic send/receive/route over iMessage — 1:1 and group chats, attachments, rich links, tapbacks, typing indicators, location pins, webhook subscriptions and events.

Event Specifications 1

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

Chert Webhooks

ASYNCAPI

Security Posture 2

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

Chert Authentication

http/hmac · 2 schemes

SECURITY

Chert Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

GettingStarted

SignUp

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

X-MCPServerCandidate

X-MCPServerCandidate

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

ErrorCatalog

Conventions

Idempotency

Webhooks

Lifecycle

DataModel

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 2

The organization behind the API

Website

Website

Blog

Blog

Source (apis.yml)

aid: chert
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - 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
  - sandbox
  generated: '2026-09-03'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/chert.png
name: Chert
description: Chert is iMessage infrastructure for reaching people at scale. Its Messaging API lets teams programmatically
  send, receive, route, and observe real iMessage conversations — blue-bubble threads from verified numbers with typing indicators,
  tapback reactions, reply context, multi-recipient group threads, SMS fallback, file attachments, rich-link previews, one-time
  location pins, and delivery receipts. Chert also ships native integrations for Salesforce, HubSpot, and Slack, plus webhook
  subscriptions and an event stream (message.received, reaction.added/removed) for real-time inbound replies. Auth is bearer
  token or HMAC-SHA256 request signing; writes support an idempotency_key. Chert is a Y Combinator (Spring 2026) company based
  in the San Francisco Bay Area.
url: https://raw.githubusercontent.com/api-evangelist/chert/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-18'
tags:
- Company
- Messaging
- iMessage
- Communications
- Conversational
- Webhook
- CRM Integration
tags_raw:
- Company
- Messaging
- iMessage
- Communications
- Conversational
- Webhooks
- CRM Integration
- API
apis:
- name: Chert Messaging API
  description: Programmatic send/receive/route over iMessage — 1:1 and group chats, attachments, rich links, tapbacks, typing
    indicators, location pins, webhook subscriptions and events.
  humanURL: https://docs.trychert.com/api/overview
  baseURL: https://console.trychert.com/api/v1
  tags:
  - Messaging
  - iMessage
  - Webhook
  tags_raw:
  - Messaging
  - iMessage
  - Webhooks
  properties:
  - type: Documentation
    url: https://docs.trychert.com
  - type: APIReference
    url: https://docs.trychert.com/api/overview
  - type: Quickstart
    url: https://docs.trychert.com/api/quickstart
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://www.trychert.com/
- type: DeveloperPortal
  url: https://console.trychert.com
- type: Documentation
  url: https://docs.trychert.com
- type: APIReference
  url: https://docs.trychert.com/api/overview
- type: GettingStarted
  url: https://docs.trychert.com/quickstart
- type: SignUp
  url: https://console.trychert.com
- type: Support
  url: https://www.trychert.com/contact
- type: Blog
  url: https://www.trychert.com/blog
- type: GitHubOrganization
  url: https://github.com/cherthq
- type: TermsOfService
  url: https://www.trychert.com/terms
- type: PrivacyPolicy
  url: https://www.trychert.com/privacy
- type: LLMsTxt
  url: llms/chert-llms.txt
- type: Authentication
  url: authentication/chert-authentication.yml
- type: ErrorCatalog
  url: errors/chert-error-codes.yml
- type: Conventions
  url: conventions/chert-conventions.yml
- type: Idempotency
  url: conventions/chert-conventions.yml
- type: Webhooks
  url: asyncapi/chert-webhooks.yml
- type: Lifecycle
  url: lifecycle/chert-lifecycle.yml
- type: X-MCPServerCandidate
  url: mcp/chert-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: Sandbox
  url: sandbox/chert-sandbox.yml
- type: DataModel
  url: data-model/chert-data-model.yml
- type: DomainSecurity
  url: security/chert-domain-security.yml
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence

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