generated: '2026-07-27'
method: searched
source: >-
  NYISO Metering API User Guide (section 2.1-2.3) and NYISO Finance APIs User's
  Guide v1.2 DRAFT (section 2.1-2.3), plus anonymous HTTP probes of every NYISO
  host on 2026-07-27
docs: https://www.nyiso.com/manuals-tech-bulletins-user-guides
summary:
  types:
  - none
  - http
  - mutualTLS
  api_key_in: []
  oauth2_flows: []
  note: >-
    NYISO runs two completely different authentication postures on two
    completely different surfaces. The open data surfaces have no authentication
    at all. The REST APIs use documented two-factor authentication - HTTP Basic
    with an MIS user account plus a NAESB-accredited client certificate. There is
    no API key, no OAuth 2.0, no OpenID Connect and no bearer token anywhere in
    the NYISO estate, and no /.well-known/ discovery document exists to describe
    one.
surfaces:
- surface: MIS public data archive
  base_url: http://mis.nyiso.com/public
  scheme: none
  description: >-
    Fully anonymous HTTP/HTTPS GET. No account, no key, no application, no
    referrer check and no licence click-through. Verified by anonymous probe on
    2026-07-27 - daily CSV and monthly ZIP files returned 200 text/csv with no
    credentials presented.
  evidence: http://mis.nyiso.com/public/csv/rtfuelmix/20260726rtfuelmix.csv returned 200
- surface: OASIS postings
  base_url: https://oasis-postings.nyiso.com
  scheme: none
  description: >-
    Anonymously readable object store. An unauthenticated ListBucket request
    returned 200 application/xml and individual posting objects returned 200.
  evidence: https://oasis-postings.nyiso.com/ACTIVE_TRANSMISSION_NODE/CSV/activetransmissionnodes.csv returned 200
- surface: Finance APIs and Metering API
  base_url: https://api.nyiso.com
  scheme: two-factor - HTTP Basic plus NAESB client certificate
  description: >-
    Restricted to NYISO market participants. Both published user guides state the
    same requirement verbatim - "A valid MIS user account and associated password
    must be provided using Basic authentication" and "The NAESB certificate
    associated with the MIS user account must be provided with each request".
    All endpoints answered 401 Authorization Required to anonymous probes.
  evidence: https://api.nyiso.com/finance/metering/v1/powerMetering returned 401
schemes:
- name: MISBasicAuth
  type: http
  scheme: basic
  in: header
  parameter: Authorization
  description: >-
    HTTP Basic credential carrying a valid NYISO Market Information System (MIS)
    user account and its password. The account must hold the relevant metering or
    settlement privileges, granted by the participant's own Marketplace
    administrator per the NYISO Settlement Data Applications User's Guide.
  sources:
  - https://www.nyiso.com/documents/20142/27889215/NYISO%20Metering%20API%20User%20Guide.pdf/d8ed36d3-1a40-9584-6961-3fdb845ca4fa
  - https://www.nyiso.com/documents/20142/45334160/NYISO%20Finance%20APIs%20User's%20Guide%20v1.2%20-%20DRAFT.pdf/4f0de58a-783d-a317-64fe-caed77ba61fa
- name: NAESBClientCertificate
  type: mutualTLS
  description: >-
    A digital certificate issued by a NAESB-Authorized Certification Authority
    and bound to the MIS user account, presented on every request. This is the
    second factor - Basic credentials alone are not sufficient. Certificate
    acquisition and MIS account binding are described in the NYISO Market
    Participant User's Guide (MPUG).
  sources:
  - https://www.nyiso.com/documents/20142/3625950/mpug.pdf
- name: None
  type: none
  description: >-
    The MIS public archive and the OASIS postings bucket require no
    authentication of any kind.
transport:
  documented: HTTPS 1.1 over TLS 1.2
  observed: >-
    api.nyiso.com and apitest.nyiso.com negotiate both TLS 1.2 and TLS 1.3 as of
    the 2026-07-27 probe; the guides state TLS 1.2 as the documented minimum.
  note: >-
    mis.nyiso.com also serves the public archive over plain HTTP, which is how
    NYISO's own list pages link it.
onboarding:
  self_serve: false
  path: >-
    Become a registered NYISO Market Participant, obtain an MIS user account with
    metering/settlement privileges through your organization's Marketplace
    administrator, then obtain a NAESB-accredited digital certificate bound to
    that account. There is no developer sign-up form and no anonymous trial - the
    market-trial host apitest.nyiso.com is credentialed too.
  contact: Stakeholder_Services@nyiso.com / +1 518-356-6060
  guides:
  - https://www.nyiso.com/documents/20142/3625950/mpug.pdf
  - https://www.nyiso.com/documents/20142/3625950/SDA_UG.pdf
discovery:
  well_known_openid_configuration: 404
  well_known_oauth_authorization_server: 404
  note: See well-known/nyiso-well-known.yml for the full probe record.