Checkmate website screenshot

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 APIs 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 19 more developer resources.

🌐 Visit website 📡 Source on GitHub
40.3/100 developing ▬ flat Agent 25/100 agent aware saas Full breakdown ↓
scored 2026-08-30 · rubric v0.17.2
AccessSelf serve
1 APIs 1 MCP Servers
CompanyConsumerCommerceE-CommerceShoppingDiscount CodesCouponsMerchantsMCPAgentic CommerceRetail

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-08-30 · rubric v0.17.2
Composite quality — 40.3/100 · developing
Contract Quality 10.4 / 21
Developer Ergonomics 8.0 / 17
Access Clarity 5.8 / 17
Operational Transparency 1.2 / 11
Contract Governance 0.5 / 10
Discoverability 6.5 / 9
Regulatory Posture 7.3 / 15
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 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 Surface 0 / 5
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.
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/.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/checkmate: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

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 4

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

API Collection

OPEN COLLECTION

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

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
WellKnown
 LLMsTxt
LLMsTxt
 MCPServer
MCPServer
 AgentSkill
AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

ErrorCatalog
ErrorCatalog
 Conventions
Conventions
 Idempotency
Idempotency
 Conformance
Conformance
 Lifecycle
Lifecycle
 DataModel
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 2

Pricing, plans, and the legal terms of use

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)

apis.yml Raw ↑ 
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: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  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: 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

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