Primitive

Primitive is a company surfaced as a portfolio company of y-combinator and added to the API Evangelist network as a stub for enrichment. This profile is a lead awaiting the enrichment pipeline.

Primitive publishes 22 API contracts indexed on the APIs.io network, including Account API, Agent API, CLI API, and 19 more. Tagged areas include Company and A2A.

The Primitive catalog on APIs.io includes 1 event-driven AsyncAPI specification and 1 Spectral governance ruleset.

📡 Profile data on GitHub

30.4/100 thin ▬ flat Agent 73/100 agent ready Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

1 published contract 1 MCP Servers 2 Agent Skills

Company A2A

What this lets a business do 2

Business capabilities this provider's published APIs can perform, derived from its own contracts. Browse all capabilities →

Agent Infrastructure & Agentic Commerce

AE-100

AgentPaymentsRegistries

POST /agent/signup/verify POST /agent/accounts POST /x402/email-challenges GET /x402/spend-policy

Developer Platform & API Ecosystem Management

BC-4270

EndpointsWebhook Deliveries

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 30.4/100 · thin

Contract Quality 11.8 / 19

Developer Ergonomics 1.2 / 15

Access Clarity 0.0 / 15

Operational Transparency 1.0 / 10

Contract Governance 2.9 / 9

Discoverability 2.9 / 8

Regulatory Posture 0.9 / 15

Create-or-Update Ergonomics 6.1 / 10

Agent readiness — 73/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 4 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 8 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 6 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

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/.

Show this score on your site.

It updates itself when the score changes. Paste this where you link to your API docs:

<a href="https://apis.io/providers/primitive/"><img src="https://apis.io/badge/primitive/card.svg" alt="Primitive on APIs.io — Kin Score by API Evangelist"></a>

Other styles, a README pill and a shields.io endpoint are on the badge page.

Raise your score.

Agent readiness — checks not met, largest first (exact, from this profile):

Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
Documented Reversibility +6 pts — a reversal operation in the contract, graded up when a window is documented too
Pagination +5 pts — share of collection GETs (an array, or one wrapped in data/items/results ...) that declare a page/limit/offset/cursor parameter, a Link header or a next/cursor field; na with no collection GETs
Agentic Commerce Well-Known Document +5 pts — a parsing /.well-known/ucp.json or acp.json declaring a version and at least one service, OR (0.27) a live x402 payment challenge from _data/x402-adoption.json — `self` when its endpoints are on the provider's own domain, `platform` when they are on a vendor's
Dry-Run / Simulate Mode +4 pts — OpenAPI: destructive operations expose a dry_run / simulate / preview / validate_only parameter
Consent & Bot Identity +3 pts — common[].type includes AIPREF, ContentSignal, WebBotAuth, or HTTPMessageSignatures

Kin Score — facets with the most composite points still available (weight × headroom):

Access Clarity scores 0.0 — up to +20.0 composite points
Developer Ergonomics scores 8.3 — up to +18.3 composite points
Operational Transparency scores 10.5 — up to +11.6 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

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 the provider profile at artifacts.apis.io/primitive/apis.yml: open an issue on github.com/api-evangelist/primitive to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 6

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Agent2Agent

measured — observed by APIs.io (conformant)

Model Context Protocol (MCP)

measured — observed by APIs.io (verified)

Agent Skills

measured — observed by APIs.io (published)

OAuth 2.0 Protected Resource Metadata

measured — observed by APIs.io (verified)

Dynamic Client Registration

measured — observed by APIs.io (published)

OpenAPI

measured — observed by APIs.io (published)

APIs 22

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

Primitive Account API

Manage your account settings, storage, and webhook secret

Primitive Agent API

Agent signup and authentication

Primitive CLI API

Browser-assisted CLI authentication

Primitive Demo API

Public, no-account sandbox operations that mirror authenticated endpoints with synthetic data so an agent can learn the request and response shapes before signing up.

Primitive Discovery API

Unauthenticated entry point that lists the API base URL, how to obtain credentials, and the operations callable without a token.

Primitive Domains API

Claim, verify, and manage email domains

Primitive Emails API

List, inspect, and manage received emails

Primitive Endpoints API

Manage webhook endpoints that receive email events

Primitive Filters API

Manage whitelist and blocklist filter rules

Primitive Functions API

Deploy JavaScript handlers that run on inbound mail. Each function is a single ESM module whose default export is an object with an async `fetch(request, env)` method, in the sh...

Primitive Inbox API

Check inbound email setup and processing readiness

Primitive Memories API

Durable org-scoped or function-scoped JSON key-value storage for agents and functions. Keys are caller-defined. Function scope is always addressed by the function id UUID, not b...

Primitive Payments API

Collect and pay stablecoin (USDC) payments with x402. Settlement is non-custodial: funds move directly from payer to payee on-chain via an EIP-3009 authorization the payer signs...

Primitive Registries API

The Agent Registry: ownable directories of agents, addressable by a registry-scoped handle. A registry's publish policy (owner_only, request, or open) decides whether a publish ...

Primitive Routes API

Recipient routing: route inbound mail to a single destination per recipient address. Rules bind an address pattern (exact or wildcard) to an endpoint; `function_id` routes an ad...

Primitive Search API

Semantic and hybrid search across received and sent mail

Primitive Sending API

Send outbound emails through the Primitive API

Primitive Service API

Operational endpoints such as the unauthenticated health/liveness probe.

Primitive Templates API

Public Function template registry reads used to browse installable agent templates.

Primitive Threads API

Conversation threads spanning received and sent emails

Primitive Wake API

Wake scheduling: schedule and send typed wake commands to your own functions over real DKIM-signed email on a cron cadence, and manage the per-target allowlist that authorizes w...

Primitive Webhook Deliveries API

View and replay webhook delivery attempts

Scroll for all 22

Open Collections 22

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

Primitive Account API

OPEN COLLECTION

Primitive Account Agent API

OPEN COLLECTION

Primitive Account CLI API

OPEN COLLECTION

Primitive Account Demo API

OPEN COLLECTION

Primitive Account Discovery API

OPEN COLLECTION

Primitive Account Domains API

OPEN COLLECTION

Primitive Account Emails API

OPEN COLLECTION

Primitive Account Endpoints API

OPEN COLLECTION

Primitive Account Filters API

OPEN COLLECTION

Primitive Account Functions API

OPEN COLLECTION

Primitive Account Inbox API

OPEN COLLECTION

Primitive Account Memories API

OPEN COLLECTION

Primitive Account Payments API

OPEN COLLECTION

Primitive Account Registries API

OPEN COLLECTION

Primitive Account Routes API

OPEN COLLECTION

Primitive Account Search API

OPEN COLLECTION

Primitive Account Sending API

OPEN COLLECTION

Primitive Account Service API

OPEN COLLECTION

Primitive Account Templates API

OPEN COLLECTION

Primitive Account Threads API

OPEN COLLECTION

Primitive Account Wake API

OPEN COLLECTION

Primitive Account Webhook Deliveries API

OPEN COLLECTION

Scroll for all 22

MCP Servers 1

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

Primitive MCP Server

Remote MCP server at www.primitive.dev over streamable HTTP; 14 tools listed.

MCP SERVER

Agent Skills 2

Packaged agent skills for driving this provider's APIs from an AI assistant.

primitive-chat

AGENT SKILL

primitive-inbox

AGENT SKILL

Event Specifications 1

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

Primitive Webhooks

ASYNCAPI

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Primitive API Rules

72 rules · 52 errors 15 warnings 5 info

SPECTRAL

OpenAPI Overlays 1

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

Primitive Openapi Overlay

3 actions · update · primitive-openapi-original.json

DERIVED

Security Posture 3

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

Primitive Authentication

apiKey/http · 2 schemes

SECURITY

Primitive Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Primitive Vulnerability Disclosure

security.txt · contact published

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Primitive Agentic Access

129 operations · 76 acting · 1 human-in-the-loop

129 operations · 76 acting

AGENTIC

Resources

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

AgentSkill

AgentSkill

MCPServer

MCPServer

Build 1

SDKs, sample code, and the tooling you integrate with

PostmanWorkspace

PostmanWorkspace

Other 3

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Overlay

Overlay

AgentCard

AgentCard

Source (apis.yml)

aid: primitive
name: Primitive
description: Primitive is a company surfaced as a portfolio company of y-combinator and added to the API Evangelist network
  as a stub for enrichment. This profile is a lead awaiting the enrichment pipeline.
url: https://raw.githubusercontent.com/api-evangelist/primitive/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
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
  - security
  - sandbox
  generated: '2026-11-06'
  method: derived
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-17'
tags:
- Company
- A2A
apis:
- aid: primitive:primitive-account-api
  name: Primitive Account API
  description: Manage your account settings, storage, and webhook secret
  tags:
  - Account
  properties:
  - type: OpenAPI
    url: openapi/primitive-account-api-openapi.yml
- aid: primitive:primitive-agent-api
  name: Primitive Agent API
  description: Agent signup and authentication
  tags:
  - Agents
  tags_raw:
  - Agent
  properties:
  - type: OpenAPI
    url: openapi/primitive-agent-api-openapi.yml
- aid: primitive:primitive-cli-api
  name: Primitive CLI API
  description: Browser-assisted CLI authentication
  tags:
  - CLI
  properties:
  - type: OpenAPI
    url: openapi/primitive-cli-api-openapi.yml
- aid: primitive:primitive-demo-api
  name: Primitive Demo API
  description: Public, no-account sandbox operations that mirror authenticated endpoints with synthetic data so an agent can
    learn the request and response shapes before signing up.
  tags:
  - Demo
  properties:
  - type: OpenAPI
    url: openapi/primitive-demo-api-openapi.yml
- aid: primitive:primitive-discovery-api
  name: Primitive Discovery API
  description: Unauthenticated entry point that lists the API base URL, how to obtain credentials, and the operations callable
    without a token.
  tags:
  - Discovery
  properties:
  - type: OpenAPI
    url: openapi/primitive-discovery-api-openapi.yml
- aid: primitive:primitive-domains-api
  name: Primitive Domains API
  description: Claim, verify, and manage email domains
  tags:
  - Domains
  properties:
  - type: OpenAPI
    url: openapi/primitive-domains-api-openapi.yml
- aid: primitive:primitive-emails-api
  name: Primitive Emails API
  description: List, inspect, and manage received emails
  tags:
  - Email
  tags_raw:
  - Emails
  properties:
  - type: OpenAPI
    url: openapi/primitive-emails-api-openapi.yml
- aid: primitive:primitive-endpoints-api
  name: Primitive Endpoints API
  description: Manage webhook endpoints that receive email events
  tags: []
  tags_raw:
  - Endpoints
  properties:
  - type: OpenAPI
    url: openapi/primitive-endpoints-api-openapi.yml
- aid: primitive:primitive-filters-api
  name: Primitive Filters API
  description: Manage whitelist and blocklist filter rules
  tags:
  - Filters
  properties:
  - type: OpenAPI
    url: openapi/primitive-filters-api-openapi.yml
- aid: primitive:primitive-functions-api
  name: Primitive Functions API
  description: 'Deploy JavaScript handlers that run on inbound mail. Each function

    is a single ESM module whose default export is an object with an

    async `fetch(request, env)` method, in the shape of a Workers-style

    handler. Primitive signs each delivery and forwards the

    `Primitive-Signature` header to the handler; verify the raw request

    body with `PRIMITIVE_WEBHOOK_SECRET` before trusting the parsed event.

    The `event` field is `email.received` for normal inbound mail, or a

    machine-mail type (`email.bounced`, `email.tls_report`,

    `email.dmarc_report`, `email.dmarc_failure`) for bounces and reports;

    the payload shape is otherwise identical. Code runs on

    Primitive''s edge runtime; there is no infrastructure to manage.

    Secrets land in `env` as encrypted bindings and are refreshed on

    every redeploy.'
  tags:
  - Functions
  properties:
  - type: OpenAPI
    url: openapi/primitive-functions-api-openapi.yml
- aid: primitive:primitive-inbox-api
  name: Primitive Inbox API
  description: Check inbound email setup and processing readiness
  tags:
  - Inbox
  properties:
  - type: OpenAPI
    url: openapi/primitive-inbox-api-openapi.yml
- aid: primitive:primitive-memories-api
  name: Primitive Memories API
  description: 'Durable org-scoped or function-scoped JSON key-value storage for

    agents and functions. Keys are caller-defined. Function scope is

    always addressed by the function id UUID, not by function name.'
  tags:
  - Memories
  properties:
  - type: OpenAPI
    url: openapi/primitive-memories-api-openapi.yml
- aid: primitive:primitive-payments-api
  name: Primitive Payments API
  description: 'Collect and pay stablecoin (USDC) payments with x402. Settlement is

    non-custodial: funds move directly from payer to payee on-chain via an

    EIP-3009 authorization the payer signs with their own key, and Primitive

    never holds funds. The payee registers a payout address and creates a

    challenge; the payer signs and settles it under a configurable spend

    policy (kill-switch, per-payment and per-day caps, payee allowlist).'
  tags:
  - Payments
  properties:
  - type: OpenAPI
    url: openapi/primitive-payments-api-openapi.yml
- aid: primitive:primitive-registries-api
  name: Primitive Registries API
  description: 'The Agent Registry: ownable directories of agents, addressable by a

    registry-scoped handle. A registry''s publish policy (owner_only, request,

    or open) decides whether a publish lists immediately or pends owner

    approval. An agent is defined once with a globally unique,

    reachability-verified address, then published into any registry under a

    handle. Discovery reads (list, resolve, get) are public for public

    registries; managing a registry and moderating requests use the owner''s

    API key.'
  tags:
  - Registries
  properties:
  - type: OpenAPI
    url: openapi/primitive-registries-api-openapi.yml
- aid: primitive:primitive-routes-api
  name: Primitive Routes API
  description: 'Recipient routing: route inbound mail to a single destination per recipient

    address. Rules bind an address pattern (exact or wildcard) to an endpoint;

    `function_id` routes an address to a function, minting its route-target

    endpoint.'
  tags:
  - Routes
  properties:
  - type: OpenAPI
    url: openapi/primitive-routes-api-openapi.yml
- aid: primitive:primitive-search-api
  name: Primitive Search API
  description: Semantic and hybrid search across received and sent mail
  tags:
  - Search
  properties:
  - type: OpenAPI
    url: openapi/primitive-search-api-openapi.yml
- aid: primitive:primitive-sending-api
  name: Primitive Sending API
  description: Send outbound emails through the Primitive API
  tags:
  - Sending
  properties:
  - type: OpenAPI
    url: openapi/primitive-sending-api-openapi.yml
- aid: primitive:primitive-service-api
  name: Primitive Service API
  description: Operational endpoints such as the unauthenticated health/liveness probe.
  tags:
  - Services
  tags_raw:
  - Service
  properties:
  - type: OpenAPI
    url: openapi/primitive-service-api-openapi.yml
- aid: primitive:primitive-templates-api
  name: Primitive Templates API
  description: Public Function template registry reads used to browse installable agent templates.
  tags:
  - Templates
  properties:
  - type: OpenAPI
    url: openapi/primitive-templates-api-openapi.yml
- aid: primitive:primitive-threads-api
  name: Primitive Threads API
  description: Conversation threads spanning received and sent emails
  tags:
  - Threads
  properties:
  - type: OpenAPI
    url: openapi/primitive-threads-api-openapi.yml
- aid: primitive:primitive-wake-api
  name: Primitive Wake API
  description: 'Wake scheduling: schedule and send typed wake commands to your own

    functions over real DKIM-signed email on a cron cadence, and manage the

    per-target allowlist that authorizes which senders may wake a function.'
  tags:
  - Wake
  properties:
  - type: OpenAPI
    url: openapi/primitive-wake-api-openapi.yml
- aid: primitive:primitive-webhook-deliveries-api
  name: Primitive Webhook Deliveries API
  description: View and replay webhook delivery attempts
  tags:
  - Webhook Deliveries
  properties:
  - type: OpenAPI
    url: openapi/primitive-webhook-deliveries-api-openapi.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: PostmanWorkspace
  url: https://www.postman.com/kinlaneapi/primitive/overview
- type: CapabilityMap
  url: capabilities/primitive-capability-edges.yml
  name: Primitive Business Capability Map
- type: AgentSkill
  url: skills/primitive-chat.md
- type: MCPServer
  url: mcp/primitive-mcp.yml
- type: Overlay
  url: overlays/primitive-openapi-overlay.yaml
- type: AgentCard
  url: a2a/primitive-a2a.yml
  name: A2A Agent Card
  description: Agent Card served at /.well-known/agent-card.json (conformant against A2A 1.0.0).
x-a2a:
  verified: true
  probed: '2026-09-26'
  url: https://primitive.dev/.well-known/agent-card.json
  grade: conformant
  protocol_version: 0.3.0
  control: 404

Primitive API — frequently asked questions

Does Primitive have an API?

Yes. APIs.io lists 22 APIs from Primitive, including Primitive Account API, Primitive Agent API and Primitive CLI API, and 19 more.

Is there an OpenAPI specification for the Primitive API?

Yes. APIs.io indexes 22 OpenAPI specifications for Primitive, each linked for download from this page.

How do I authenticate with the Primitive API?

Primitive documents its authentication (apiKey/http · 2 schemes). The details are profiled on APIs.io as Primitive Authentication.

Does Primitive have an MCP server?

Yes. APIs.io lists 1 MCP server for Primitive: Remote MCP server at www.primitive.dev over streamable HTTP; 14 tools listed.

Is the Primitive API ready for AI agents?

Primitive has a Kin Score of 30.4 out of 100 (thin) and an Agent Readiness score of 73.2 (agent-ready), scored by API Evangelist on 2026-11-06.

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/primitive"

All providers

curl "https://apis.io/api/v1/providers?limit=25"

Every operation they expose

curl "https://apis.io/api/v1/providers/primitive/operations?limit=25"

How their score was established

curl "https://apis.io/api/v1/providers/primitive/evidence"

Calls without X-API-Key need no key. Calls with it need a paid plan — get a key.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

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