Arkham Market Data API

openapi: 3.2.0
info:
  title: Arkham Marketdata API
  x-refined-note:
  - x-guidance differs across the merged source definitions and was not carried
  version: '1.0'
  description: 'Operations tagged Marketdata across 2 of this provider''s published API definitions: arkham-openapi-original.json, arkham-openapi.json. Each path carries the servers of the definition it was published in.'
servers:
- url: https://api.arkm.com/x402
tags:
- name: Market Data
paths:
  /marketdata/altcoin_index:
    get:
      summary: Get Altcoin Index
      description: Returns the current Altcoin Index value, which measures altcoin performance relative to Bitcoin.
      operationId: GetAltcoinIndexAPI
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GetAltcoinIndexResponse'
        '500':
          description: Internal Server Error
      tags:
      - Market Data
  /marketdata/altcoin-index:
    post:
      operationId: marketdata_altcoin-index
      summary: Get Arkham Altcoin Index
      tags:
      - Market Data
      x-payment-info:
        price:
          mode: fixed
          currency: USD
          amount: '0.20'
        protocols:
        - x402: {}
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties: {}
              additionalProperties:
                anyOf:
                - type: string
                - type: number
                - type: boolean
                - type: array
                  items:
                    anyOf:
                    - type: string
                    - type: number
                    - type: boolean
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema: {}
        '400':
          $ref: '#/components/responses/BadRequest400'
        '402':
          $ref: '#/components/responses/PaymentRequired402'
        '404':
          $ref: '#/components/responses/NotFound404'
        '429':
          $ref: '#/components/responses/RateLimited429'
        5XX:
          $ref: '#/components/responses/UpstreamError5xx'
      security: []
      description: Get Arkham Altcoin Index. $0.20 per call.
    servers:
    - url: https://api.arkm.com/x402
components:
  schemas:
    GetAltcoinIndexResponse:
      required:
      - altcoinIndex
      type: object
      properties:
        altcoinIndex:
          type: integer
          description: Altcoin Index value from 0 to 100. Higher values indicate altcoins are outperforming Bitcoin.
          example: 63
      example:
        altcoinIndex: 63
  responses:
    PaymentRequired402:
      description: 'Payment challenge, not an application error. Read the base64 x402 v2 challenge from PAYMENT-REQUIRED, sign it, and retry the same request with PAYMENT-SIGNATURE. If a post-payment 402 omits PAYMENT-REQUIRED, verification failed: read the new challenge, re-sign, and retry once.'
      headers:
        PAYMENT-REQUIRED:
          description: Base64-encoded x402 v2 payment requirements. Its accepts array contains the scheme, network, asset, atomic amount, and payTo address.
          schema:
            type: string
    NotFound404:
      description: The upstream Arkham resource does not exist. Fatal for the same input. Payment is not settled.
    UpstreamError5xx:
      description: Arkham failed or timed out, including 502 and 504 responses. Retry with backoff. x402 payments and MPP transaction credentials are not settled for failed requests; MPP hash credits are redeemed at admission and are not refunded automatically.
    RateLimited429:
      description: Per-wallet endpoint rate limit exceeded. Retry with at least 1 second of backoff; keep heavy endpoints at no more than 5 requests per second.
    BadRequest400:
      description: 'Fatal for the request as written: validation failed or required JSON body fields are missing. Fix the request; do not retry it unchanged. Payment is not settled.'
      content:
        application/json:
          schema:
            type: object
            required:
            - success
            - error
            properties:
              success:
                type: boolean
                enum:
                - false
              error:
                type: string
              issues:
                type: array
                description: Per-field validation issues, present when schema validation produced them.
  securitySchemes:
    siwx:
      type: apiKey
      in: header
      name: SIGN-IN-WITH-X
x-refined-from:
- arkham-openapi-original.json
- arkham-openapi.json