Checkmate Merchants API

openapi: 3.2.0
info:
  version: 1.0.0
  title: OpenStock Health Merchants API
  description: 'API provided by Checkmate to partners to provide access to merchant codes and shopper purchase history. All endpoints are POST with batched request/response shapes. Authenticate with `Authorization: Bearer <api_key>`. Ask partner representative for the API key.'
servers:
- url: https://api.openstock.sh
  description: Current environment
tags:
- name: Merchants
paths:
  /v1/merchants/search:
    post:
      tags:
      - Merchants
      summary: Batch merchant search
      description: 'Search for merchants by name (fuzzy) or domain (exact match). Up to 20 queries per request. Each query carries its own `query_id` that is echoed back so callers can correlate responses. Each result contains an `items` array with matched merchants. Name queries return up to `limit` items per result (default 5, max 20). Misses return a single item with `id: null` — there are no 404s.'
      security:
      - BearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MerchantSearchRequest'
      responses:
        '200':
          description: 'Per-query results. Each result has an `items` array. A name query with limit > 1 may produce multiple items. Misses have id: null.'
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MerchantSearchResponse'
        '400':
          description: Invalid request body or query cap exceeded (max 50 queries)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Missing or invalid API key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '429':
          description: Too many requests. Rate limits are determined on a per partner basis.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
  /v1/merchants/codes:
    post:
      tags:
      - Merchants
      summary: Batch merchant offer codes
      description: Retrieve ranked offer codes for a set of merchants. Up to 20 queries per request. Each result contains an `items` array of codes; misses return an empty `items` array. Add an `idempotency_key` to deduplicate requests; we suggest using `sha256(user_email + date)` or similar.
      security:
      - BearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MerchantCodesRequest'
      responses:
        '200':
          description: Per-query results. Each result has an `items` array of codes. Misses return an empty `items` array.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MerchantCodesResponse'
        '400':
          description: Invalid request body, missing idempotency_key, or query cap exceeded (max 20)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Missing or invalid API key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '429':
          description: Too many requests. Rate limits are determined on a per partner basis.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
components:
  schemas:
    MerchantCodesResponse:
      type: object
      properties:
        results:
          type: array
          items:
            $ref: '#/components/schemas/MerchantCodesResult'
      required:
      - results
    ErrorResponse:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
              example: VALIDATION_ERROR
            message:
              type: string
              example: Request body is invalid
          required:
          - code
          - message
      required:
      - error
    MerchantCodesRequest:
      type: object
      properties:
        queries:
          type: array
          items:
            $ref: '#/components/schemas/MerchantCodesQuery'
          minItems: 1
          maxItems: 20
          description: Batch of codes queries (1–20)
      required:
      - queries
    OfferCode:
      type: object
      properties:
        code:
          type:
          - string
          - 'null'
          example: SAVE10
          description: Promo code string, or null for codeless offers
        probability:
          type: number
          minimum: 0
          maximum: 1
          example: 0.92
          description: Estimated probability (0–1) that the code will work at checkout
        single_use:
          type: boolean
          example: false
          description: True when the code expires after one redemption
        value_type:
          type: string
          enum:
          - percent
          - fixed
          - free_shipping
          - unknown
          example: percent
          description: How the discount value is expressed
        value_amount:
          type:
          - number
          - 'null'
          example: 10
          description: Numeric discount amount; semantics depend on value_type (e.g. 10 = 10% or $10)
        currency:
          type:
          - string
          - 'null'
          example: USD
          description: ISO 4217 currency code, present when value_type is "fixed"
        conditions:
          type: array
          items:
            type: string
          example:
          - minimum_subtotal
          description: Machine-readable condition tags (e.g. minimum_subtotal, product_restricted, applies_on_subscription)
        redirect_url:
          type:
          - string
          - 'null'
          example: https://go.checkmate.com/r/acme?code=SAVE10&ref=ck_partner_api
          description: Checkmate affiliate-attributed deep-link; null when unavailable
        expires_at:
          type:
          - number
          - 'null'
          example: null
          description: Unix timestamp (ms) when the code expires, or null when it does not expire
        last_success:
          type:
          - string
          - 'null'
          example: '2026-06-16T17:00:00.000Z'
          description: ISO 8601 UTC timestamp of the most recent successful checkout with this code, or null when never observed
        description:
          type:
          - string
          - 'null'
          example: 10% off your first order
          description: Human-readable description of the offer or null
        apply_count:
          type:
          - number
          - 'null'
          example: 1280
          description: Number of times this code has been applied at checkout, or null when not tracked (e.g. campaign/minted codes)
        success_count:
          type:
          - number
          - 'null'
          example: 940
          description: Number of times this code applied successfully (yielded a saving), or null when not tracked (e.g. campaign/minted codes)
      required:
      - code
      - probability
      - single_use
      - value_type
      - value_amount
      - currency
      - conditions
      - redirect_url
      - expires_at
      - last_success
      - description
      - apply_count
      - success_count
    MerchantSearchItem:
      type: object
      properties:
        id:
          type:
          - string
          - 'null'
          example: 01hz4vdrcnxhfmfcvy3rfqk1fp
          description: Checkmate merchant ID, or null when not found
        name:
          type:
          - string
          - 'null'
          example: Acme Corp
          description: Merchant display name, or null when no match
        domains:
          type: array
          items:
            type: string
          example:
          - acme.com
          - acme.co.uk
          description: Merchant domains
        estimated_shipping:
          $ref: '#/components/schemas/EstimatedShipping'
      required:
      - id
      - name
      - domains
      - estimated_shipping
    MerchantCodesQuery:
      type: object
      properties:
        query_id:
          type: string
          minLength: 1
          example: q1
          description: Caller-supplied opaque identifier correlated back in results
        merchant_id:
          type: string
          minLength: 1
          example: 01hz4vdrcnxhfmfcvy3rfqk1fp
          description: Checkmate merchant ID obtained from the search endpoint
        idempotency_key:
          type: string
          minLength: 1
          example: a3f1e2d4b5c6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c9d0e1f2
          description: Deduplication key for this query. We suggest using `sha256(user_email + date)` or similar.
      required:
      - query_id
      - merchant_id
      - idempotency_key
    MerchantCodesResult:
      type: object
      properties:
        query_id:
          type: string
          example: q1
        items:
          type: array
          items:
            $ref: '#/components/schemas/OfferCode'
          description: Ranked list of offer codes (minted / static / codeless / partnership / public). Empty array on miss.
      required:
      - query_id
      - items
    MerchantSearchResponse:
      type: object
      properties:
        results:
          type: array
          items:
            $ref: '#/components/schemas/MerchantSearchResult'
      required:
      - results
    EstimatedShipping:
      type:
      - object
      - 'null'
      properties:
        unit:
          type: string
          enum:
          - days
          example: days
          description: Unit for all shipping time values in this object
        median:
          type: number
          example: 6
          description: Median days to deliver
        q1:
          type:
          - number
          - 'null'
          example: 3
          description: First quartile (25th percentile) days to deliver, or null when unknown
        q3:
          type:
          - number
          - 'null'
          example: 10
          description: Third quartile (75th percentile) days to deliver, or null when unknown
      required:
      - unit
      - median
      - q1
      - q3
      description: Estimated shipping time statistics, or null when unknown
    MerchantSearchResult:
      type: object
      properties:
        query_id:
          type: string
          example: q1
        items:
          type: array
          items:
            $ref: '#/components/schemas/MerchantSearchItem'
          minItems: 1
          description: 'Matched merchants for this query. Always contains at least one entry. Misses return a single entry with `id: null`; name queries with `limit > 1` may return multiple entries.'
      required:
      - query_id
      - items
    MerchantSearchRequest:
      type: object
      properties:
        queries:
          type: array
          items:
            $ref: '#/components/schemas/MerchantSearchQuery'
          minItems: 1
          maxItems: 50
          description: Batch of search queries (1–50). Each query returns a result with an `items` array. Name queries with `limit > 1` may yield multiple items. Misses return an `items` array with a single entry where `id` is null.
      required:
      - queries
    MerchantSearchQuery:
      type: object
      properties:
        query_id:
          type: string
          minLength: 1
          example: q1
          description: Caller-supplied opaque identifier correlated back in results
        type:
          type: string
          enum:
          - name
          - domain
          example: name
          description: '"name" triggers fuzzy search; "domain" is an exact-match lookup'
        value:
          type: string
          minLength: 1
          example: Acme
          description: 'Search term: merchant name fragment or bare domain'
        region:
          type: string
          example: US
          description: Optional ISO 3166-1 alpha-2 region filter (name queries only)
        limit:
          type: integer
          minimum: 1
          maximum: 20
          default: 5
          example: 5
          description: Maximum number of results to return for this query (name queries only, domain queries always return at most one result). Defaults to 5.
      required:
      - query_id
      - type
      - value