Checkmate

Checkmate is a shopping intelligence and data company whose network powers three products: Checkmate for consumers (a browser extension and mobile app that automatically finds the best price and applies working discount codes across 284,000+ merchants for 5M+ monthly shoppers), Mate for brands (AI-powered revenue intelligence), and OpenStock for publishers and agents. OpenStock is a commerce API and Model Context Protocol (MCP) server that exposes the entire Checkmate network through a single endpoint — letting AI agents, shopping copilots, and applications discover merchants, pull live catalogues and offers, generate real merchant-backed discount codes, check availability, and attribute orders. Backed by GV (Google Ventures).

Checkmate publishes 3 API contracts indexed on the APIs.io network: Health API, Merchants API, and Shoppers API. Tagged areas include Company, Consumer, Commerce, E-Commerce, and Shopping.

Checkmate’s developer surface includes documentation, API reference, engineering blog, support, signup flow, authentication, and 20 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

45.3/100 developing ▲ 7.9 Agent 28/100 agent aware Front door AI 2/6 trace saas Full breakdown ↓
scored 2026-10-31 · rubric v0.25.0 · Show this score on your site →

1 published contract 1 MCP Servers 2 Agent Skills

Company Consumer Commerce E-Commerce Shopping Discount Codes Coupons Merchants MCP Agentic Commerce Retail

Kin Score

Kin Score How this is scored →
scored 2026-10-31 · rubric v0.25.0

Composite quality — 45.3/100 · developing

Contract Quality 9.8 / 21

Developer Ergonomics 8.0 / 17

Access Clarity 12.5 / 17

Operational Transparency 1.2 / 11

Contract Governance 0.5 / 10

Discoverability 5.5 / 9

Regulatory Posture 4.2 / 15

Agent readiness — 28/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 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 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

Pagination 5 / 5

Distinct Operations 3 / 3

Regulatory Posture applies to this provider. Its tags matched the Payments 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 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.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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

Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented)
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document

7 more unmet checks in the Agent Readiness table above.

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

Contract Quality scores 46.3 — up to +13.4 composite points
Operational Transparency scores 10.5 — up to +11.6 composite points
Contract Governance scores 4.5 — up to +11.5 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/checkmate/apis.yml: open an issue on github.com/api-evangelist/checkmate 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 →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Browser Extension Stores (company-published Firefox add-ons; Chrome Web Store unreadable)	builds-on	17.2 (thin)	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

APIs 3

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

Checkmate Health API

The Health API from Checkmate — 1 operation(s) for health.

Checkmate Merchants API

The Merchants API from Checkmate — 2 operation(s) for merchants.

Checkmate Shoppers API

The Shoppers API from Checkmate — 1 operation(s) for shoppers.

Open Collections 3

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

OpenStock Health API

OPEN COLLECTION

OpenStock Health Merchants API

OPEN COLLECTION

OpenStock Health Shoppers API

OPEN COLLECTION

MCP Servers 1

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

Checkmate MCP Server

OpenStock by Checkmate — "the world's largest MCP for ecommerce." A single Model Context Protocol server that exposes catalogues, offers, and merchant-backed discount-code gener...

MCP SERVER

Agent Skills 2

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

Find a merchant and mint a working discount code

AGENT SKILL

Look up a shopper's merchant history

AGENT SKILL

Pricing Plans 2

Published pricing tiers and plan structures.

Checkmate Plans Pricing

8 plans

PLANS

Checkmate Price Estimates

0 plans

PLANS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Checkmate Finops

FINOPS

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.

Checkmate Openstock Overlay

7 actions · documentation · checkmate-openstock-openapi-original.json

DERIVED

Security Posture 3

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

Checkmate Authentication

http · 1 scheme

SECURITY

Checkmate Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Checkmate Vulnerability Disclosure

security.txt · contact published

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

SignUp

SignUp

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

WellKnown

LLMsTxt

MCPServer

AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

ErrorCatalog

Conventions

Idempotency

Conformance

Lifecycle

DataModel

Access & Security 5

Authentication, authorization, and security posture

Security

Security

VulnerabilityDisclosure

VulnerabilityDisclosure

SecurityTxt

SecurityTxt

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 3

Pricing, plans, and the legal terms of use

Plans

Plans

PrivacyPolicy

PrivacyPolicy

TermsOfService

TermsOfService

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)

aid: checkmate
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://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/checkmate.png
name: Checkmate
description: 'Checkmate is a shopping intelligence and data company whose network powers three products: Checkmate for consumers
  (a browser extension and mobile app that automatically finds the best price and applies working discount codes across 284,000+
  merchants for 5M+ monthly shoppers), Mate for brands (AI-powered revenue intelligence), and OpenStock for publishers and
  agents. OpenStock is a commerce API and Model Context Protocol (MCP) server that exposes the entire Checkmate network through
  a single endpoint — letting AI agents, shopping copilots, and applications discover merchants, pull live catalogues and
  offers, generate real merchant-backed discount codes, check availability, and attribute orders. Backed by GV (Google Ventures).'
url: https://raw.githubusercontent.com/api-evangelist/checkmate/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- gv
x-tier: enriched
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-18'
tags:
- Company
- Consumer
- Commerce
- E-Commerce
- Shopping
- Discount Codes
- Coupons
- Merchants
- MCP
- Agentic Commerce
- Retail
tags_raw:
- Company
- Consumer
- Commerce
- Ecommerce
- Shopping
- Discount Codes
- Coupons
- Merchants
- MCP
- Agentic Commerce
- Retail
- API
apis:
- aid: checkmate:checkmate-health-api
  name: Checkmate Health API
  description: The Health API from Checkmate — 1 operation(s) for health.
  humanURL: https://openstock.sh
  baseURL: https://api.openstock.sh
  tags:
  - Health
  properties:
  - type: OpenAPI
    url: openapi/checkmate-health-api-openapi.yml
  - type: Documentation
    url: https://api.openstock.sh/docs
  - type: APIReference
    url: https://api.openstock.sh/docs
- aid: checkmate:checkmate-merchants-api
  name: Checkmate Merchants API
  description: The Merchants API from Checkmate — 2 operation(s) for merchants.
  humanURL: https://openstock.sh
  baseURL: https://api.openstock.sh
  tags:
  - Merchants
  properties:
  - type: OpenAPI
    url: openapi/checkmate-merchants-api-openapi.yml
  - type: Documentation
    url: https://api.openstock.sh/docs
  - type: APIReference
    url: https://api.openstock.sh/docs
- aid: checkmate:checkmate-shoppers-api
  name: Checkmate Shoppers API
  description: The Shoppers API from Checkmate — 1 operation(s) for shoppers.
  humanURL: https://openstock.sh
  baseURL: https://api.openstock.sh
  tags:
  - Shoppers
  properties:
  - type: OpenAPI
    url: openapi/checkmate-shoppers-api-openapi.yml
  - type: Documentation
    url: https://api.openstock.sh/docs
  - type: APIReference
    url: https://api.openstock.sh/docs
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Plans
  url: plans/checkmate-plans-pricing.yml
- type: Overlay
  url: overlays/checkmate-openstock-overlay.yaml
- type: Website
  url: https://joincheckmate.com
- type: DeveloperPortal
  url: https://openstock.sh
- type: Documentation
  url: https://api.openstock.sh/docs
- type: APIReference
  url: https://api.openstock.sh/docs
- type: Blog
  url: https://joincheckmate.com/blog
- type: Support
  url: mailto:support@joincheckmate.com
- type: SignUp
  url: https://joincheckmate.com/login
- type: PrivacyPolicy
  url: https://joincheckmate.com/privacy-policy
- type: TermsOfService
  url: https://joincheckmate.com/terms-conditions
- type: Security
  url: https://joincheckmate.com/security
- type: VulnerabilityDisclosure
  url: security/checkmate-vulnerability-disclosure.yml
- type: SecurityTxt
  url: well-known/checkmate-security.txt
- type: WellKnown
  url: well-known/checkmate-well-known.yml
- type: DomainSecurity
  url: security/checkmate-domain-security.yml
- type: LLMsTxt
  url: llms/checkmate-llms.txt
- type: MCPServer
  url: mcp/checkmate-mcp.yml
- type: Authentication
  url: authentication/checkmate-authentication.yml
- type: ErrorCatalog
  url: errors/checkmate-problem-types.yml
- type: Conventions
  url: conventions/checkmate-conventions.yml
- type: Idempotency
  url: conventions/checkmate-conventions.yml
- type: Conformance
  url: conformance/checkmate-conformance.yml
- type: Lifecycle
  url: lifecycle/checkmate-lifecycle.yml
- type: DataModel
  url: data-model/checkmate-data-model.yml
- 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

Checkmate API — frequently asked questions

Does Checkmate have an API?

Yes. APIs.io lists 3 APIs from Checkmate, including Checkmate Health API, Checkmate Merchants API and Checkmate Shoppers API.

Is there an OpenAPI specification for the Checkmate API?

Yes. APIs.io indexes 3 OpenAPI specifications for Checkmate, each linked for download from this page.

How do I authenticate with the Checkmate API?

Checkmate uses bearer-token authentication (http · 1 scheme). The details are profiled on APIs.io as Checkmate Authentication.

How much does the Checkmate API cost?

APIs.io lists 8 pricing plans for Checkmate, with each plan's price, limits and inclusions under Pricing Plans on this page.

Does Checkmate have an MCP server?

Yes. APIs.io lists 1 MCP server for Checkmate: OpenStock by Checkmate — "the world's largest MCP for ecommerce." A single Model Context Protocol server that exposes catalogues, offers, and merchant-backed discount-code generation across the entire

Is the Checkmate API ready for AI agents?

Checkmate has a Kin Score of 45.3 out of 100 (developing) and an Agent Readiness score of 27.9 (agent-aware), scored by API Evangelist on 2026-10-31.

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