> ## Documentation Index
> Fetch the complete documentation index at: https://docs.skinloop.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Authenticate a Steam trade URL and return the CS2 inventory

> The trade URL is validated by Skinloop and its SteamID64 is derived
server-side. The opaque session token expires after ten minutes and is
accepted only as a bearer token on the inventory endpoint.




## OpenAPI

````yaml /openapi.yaml post /v1/checkout/authenticate
openapi: 3.1.0
info:
  title: Skinloop API
  version: 1.1.0-draft
  description: |
    Public contract for Skinloop merchant payments, hosted checkout status,
    merchant dashboard reads, and merchant webhooks. Skinloop never exposes
    credentials, private identifiers, trade URLs, or client tokens.
servers:
  - url: https://api.skinloop.io
    description: Production
security: []
tags:
  - name: Payments
  - name: Checkout
  - name: Reporting
  - name: Dashboard
paths:
  /v1/checkout/authenticate:
    post:
      tags:
        - Checkout
      summary: Authenticate a Steam trade URL and return the CS2 inventory
      description: |
        The trade URL is validated by Skinloop and its SteamID64 is derived
        server-side. The opaque session token expires after ten minutes and is
        accepted only as a bearer token on the inventory endpoint.
      operationId: authenticateCheckout
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CheckoutAuthenticateRequest'
      responses:
        '200':
          description: Authenticated checkout session and normalized CS2 inventory
          headers:
            Cache-Control:
              schema:
                type: string
                const: no-store
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CheckoutInventoryResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '403':
          $ref: '#/components/responses/Forbidden'
        '413':
          $ref: '#/components/responses/PayloadTooLarge'
        '429':
          $ref: '#/components/responses/RateLimited'
        '503':
          $ref: '#/components/responses/ServiceUnavailable'
      security: []
components:
  schemas:
    CheckoutAuthenticateRequest:
      type: object
      additionalProperties: false
      required:
        - tradeUrl
      properties:
        tradeUrl:
          type: string
          minLength: 40
          maxLength: 256
          pattern: >-
            ^https://steamcommunity\.com/tradeoffer/new/\?partner=[0-9]{1,10}&token=[A-Za-z0-9_-]{5,64}$
    CheckoutInventoryResponse:
      type: object
      additionalProperties: false
      required:
        - inventory
        - unavailable
        - unavailable_count
        - collateral
        - updated_at
      properties:
        sessionToken:
          type: string
          description: Present only in the authenticate response; omitted on refresh.
        inventory:
          type: array
          items:
            $ref: '#/components/schemas/CheckoutInventoryItem'
        unavailable:
          type: array
          description: Tradable items that Skinloop cannot currently accept.
          items:
            $ref: '#/components/schemas/CheckoutUnavailableItem'
        unavailable_count:
          type: integer
          minimum: 0
          description: >-
            Total CS2 items Skinloop cannot accept, including non-tradable and
            unaccepted items.
        collateral:
          type:
            - string
            - 'null'
          pattern: ^(0\.[0-9]{2}|[1-9][0-9]*(\.[0-9]{2})?)$
        updated_at:
          type: string
          format: date-time
    CheckoutInventoryItem:
      type: object
      additionalProperties: false
      required:
        - id
        - asset_id
        - name
        - market_hash_name
        - icon_url
        - appid
        - tradable
        - offer
      properties:
        id:
          type: string
        asset_id:
          type: string
        name:
          type: string
        market_hash_name:
          type: string
        icon_url:
          type:
            - string
            - 'null'
          format: uri
        appid:
          type: integer
          enum:
            - 730
            - 252490
        tradable:
          type: boolean
          const: true
        exterior:
          type:
            - string
            - 'null'
        wear:
          type:
            - string
            - 'null'
        offer:
          type: object
          additionalProperties: false
          required:
            - accepted
            - available
            - price
            - price_minor
          properties:
            accepted:
              type: boolean
              const: true
            available:
              type: boolean
              const: true
            price:
              type: string
              pattern: ^(0\.[0-9]{2}|[1-9][0-9]*(\.[0-9]{2})?)$
            price_minor:
              type: integer
              minimum: 1
    CheckoutUnavailableItem:
      type: object
      additionalProperties: false
      required:
        - id
        - asset_id
        - name
        - market_hash_name
        - icon_url
        - appid
        - tradable
        - offer
      properties:
        id:
          type: string
        asset_id:
          type: string
        name:
          type: string
        market_hash_name:
          type: string
        icon_url:
          type: string
          format: uri
        appid:
          type: integer
          const: 730
        tradable:
          type: boolean
          const: true
        exterior:
          type:
            - string
            - 'null'
        wear:
          type:
            - string
            - 'null'
        offer:
          type: object
          additionalProperties: false
          required:
            - accepted
            - available
            - price
          properties:
            accepted:
              type: boolean
              const: false
            available:
              type: boolean
              const: false
            price:
              type: 'null'
    Error:
      type: object
      additionalProperties: false
      required:
        - error
      properties:
        error:
          type: object
          additionalProperties: false
          required:
            - code
            - message
            - request_id
          properties:
            code:
              type: string
            message:
              type: string
            request_id:
              type: string
  responses:
    BadRequest:
      description: Invalid request
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Forbidden:
      description: Checkout origin is not allowed
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    PayloadTooLarge:
      description: Checkout request body exceeds 16 KiB
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    RateLimited:
      description: Rate limit exceeded
      headers:
        Retry-After:
          schema:
            type: integer
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    ServiceUnavailable:
      description: Checkout service is not configured or unavailable
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'

````