generated: '2026-07-22'
method: searched
source: https://cmegroupclientsite.atlassian.net/wiki/spaces/EPICSANDBOX/pages/457215780/CME+Reference+Data+API+Version+3
notes: >-
  Cross-cutting request/response semantics for CME Group's cloud market data
  REST APIs (Reference Data API v3, FedWatch End-of-Day and Intraday, Term
  SOFR, Greeks and Implied Volatility, Cross Currency), captured from the CME
  Group Client Systems Wiki. No idempotency-key contract is documented (the
  public surface is read-only GET). Cross-links: authentication/, errors/,
  lifecycle/, rate-limits/.
authentication:
  style: OAuth 2.0 client-credentials Bearer token
  header: 'Authorization: Bearer <access_token>'
  detail: authentication/cme-group-authentication.yml
versioning:
  scheme: uri-path
  examples: [/refdata/v3, /fedwatch/v1, /fedwatch_rt/v1, /term-sofr-rates/v1, /greeks/v1, /xccy/v1]
pagination:
  style: page-number
  request_params:
    - name: size
      description: Results per page. Reference Data API maximum 2000 (values above 2000 fall back to 2000); market data APIs default 1000, maximum 2000 (as pageSize).
    - name: page
      description: Page to retrieve; numbering starts at 0 (Reference Data API). Market data APIs use pageNumber.
  response_metadata:
    fields: [pageSize, totalPages, pageNumber, totalElements, type, elementsInReponse]
    links: ["_links.first", "_links.prev", "_links.next", "_links.last"]
    note: _links prev/next only appear when applicable; type is always "page".
  limits:
    max_page_size: 2000
    max_response_bytes: 10485760
    over_limit_behavior: HTTP 502 — resubmit with a smaller size
idempotency:
  supported: false
  note: No idempotency-key mechanism is documented; the public cloud APIs are read-only GET surfaces (ClearPort trade submission uses its own FIXML protocol).
error_envelope:
  shape: 'errorResponse: {code, message, fault name, reason, error detail}'
  detail: errors/cme-group-problem-types.yml
query_conventions:
  reserved_characters: "/ # \\ < > and space must be percent-encoded; + is not supported (use ? as wildcard substitute); ? is a supported wildcard in Reference Data API queries"
  wildcards: ["?"]
rate_limits:
  note: No numeric per-second ceilings published for the cloud REST APIs; protocol-level MPS caps apply to iLink/MDP. See rate-limits/cme-group-rate-limits.yml.
environments:
  production:
    refdata: https://refdata.api.cmegroup.com/refdata/v3
    market_data: https://markets.api.cmegroup.com
    oauth_token: https://auth.cmegroup.com/as/token.oauth2
  new_release:
    refdata: https://refdata.api.uat.cmegroup.com/refdata/v3
    oauth_token: https://authnr.cmegroup.com/as/token.oauth2
  note: API ID credentials are environment-specific and cannot be used across environments.