openapi: 3.2.0
info:
  title: ISO New England Web Services API v1.1 Monthlylmpindex API
  version: '1.1'
  description: RESTful interface to ISO New England energy and market data. This OpenAPI document was DERIVED by API Evangelist from ISO New England's own published, machine-generated Enunciate technical documentation at https://webservices.iso-ne.com/docs/v1.1/ and the two XML Schemas it publishes (ns0.xsd, ns1.xsd, saved verbatim under schemas/). ISO New England does not publish an OpenAPI definition; the only provider-published machine-readable description of the interface is a WADL at https://webservices.iso-ne.com/api/v1.1?_wadl&_type=xml, which sits behind the same HTTP Basic authentication as the API and returned HTTP 401 to anonymous probes. Every path, method, parameter, description, media type and schema in this document is copied from the provider's published sources; nothing was invented. Each operation carries x-evidence naming the exact documentation page it came from. All feeds are available in XML and JSON, selected by adding a .xml or .json extension to the request URL or by sending an Accept header of application/xml or application/json.
  contact:
    name: ISO New England Ask ISO
    url: https://askiso.iso-ne.com/s/
  x-provenance:
    method: derived
    derived_by: API Evangelist enrichment pipeline
    derived_on: '2026-07-27'
    sources:
    - https://webservices.iso-ne.com/docs/v1.1/
    - https://webservices.iso-ne.com/docs/v1.1/ns0.xsd
    - https://webservices.iso-ne.com/docs/v1.1/ns1.xsd
    - https://www.iso-ne.com/participate/support/web-services-data
    not_provider_published: true
    note: Derived from provider-published HTML documentation and XSDs. Not an ISO New England artifact.
servers:
- url: https://webservices.iso-ne.com/api/v1.1
  description: Production base path (HTTP Basic over SSL)
security:
- basicAuth: []
tags:
- name: monthlylmpindex
  description: 4 path template(s) under /monthlylmpindex in the published ISO New England Web Services API v1.1 documentation.
paths:
  /monthlylmpindex:
    get:
      operationId: getMonthlylmpindex
      summary: Default resource
      description: Default resource. Redirects to Monthly LMP Index Info.
      tags:
      - monthlylmpindex
      responses:
        '200':
          description: Successful response.
          content:
            application/xml:
              schema:
                description: Response payload is not described in the published documentation.
            application/json:
              schema:
                description: Response payload is not described in the published documentation.
        '401':
          description: Unauthorized - HTTP Basic credentials from an ISO Express account are required. Verified by anonymous probe on 2026-07-27.
      x-evidence:
        source: https://webservices.iso-ne.com/docs/v1.1/rest.monthlylmpindex.html
        harvested: '2026-07-27'
  /monthlylmpindex/current:
    get:
      operationId: getMonthlylmpindexCurrent
      summary: Get current MonthlyLmpIndexes for Service Type
      description: Get current MonthlyLmpIndexes for Service Type.
      tags:
      - monthlylmpindex
      responses:
        '200':
          description: a WeeklyLmpIndexsElement containing the current MonthlyLmpIndexs.
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/MonthlyLmpIndexes'
            application/json:
              schema:
                $ref: '#/components/schemas/MonthlyLmpIndexes'
        '401':
          description: Unauthorized - HTTP Basic credentials from an ISO Express account are required. Verified by anonymous probe on 2026-07-27.
      x-evidence:
        source: https://webservices.iso-ne.com/docs/v1.1/rest.monthlylmpindex.current.html
        harvested: '2026-07-27'
      x-xml-element: MonthlyLmpIndexes
  /monthlylmpindex/info:
    get:
      operationId: getMonthlylmpindexInfo
      summary: Get the Service Info for Monthly LMP Index
      description: Get the Service Info for Monthly LMP Index.
      tags:
      - monthlylmpindex
      responses:
        '200':
          description: the ServiceInfoElement for Monthly LMP Index.
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/ServiceInfo'
            application/json:
              schema:
                $ref: '#/components/schemas/ServiceInfo'
        '401':
          description: Unauthorized - HTTP Basic credentials from an ISO Express account are required. Verified by anonymous probe on 2026-07-27.
      x-evidence:
        source: https://webservices.iso-ne.com/docs/v1.1/rest.monthlylmpindex.info.html
        harvested: '2026-07-27'
      x-xml-element: ServiceInfo
  /monthlylmpindex/year/{year}:
    get:
      operationId: getMonthlylmpindexYearByYear
      summary: Get an entire Years MonthlyLmpIndexs
      description: Get an entire Years MonthlyLmpIndexs.
      tags:
      - monthlylmpindex
      responses:
        '200':
          description: a WeeklyLmpIndexsElement containing the MonthlyLmpIndexs.
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/MonthlyLmpIndexes'
            application/json:
              schema:
                $ref: '#/components/schemas/MonthlyLmpIndexes'
        '401':
          description: Unauthorized - HTTP Basic credentials from an ISO Express account are required. Verified by anonymous probe on 2026-07-27.
      x-evidence:
        source: https://webservices.iso-ne.com/docs/v1.1/rest.monthlylmpindex.year.year.html
        harvested: '2026-07-27'
      x-xml-element: MonthlyLmpIndexes
      parameters:
      - name: year
        in: path
        required: true
        schema:
          type: string
components:
  schemas:
    MonthlyLmpIndexes:
      type: object
      properties:
        MonthlyLmpIndex:
          type: array
          items:
            $ref: '#/components/schemas/MonthlyLmpIndex'
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_MonthlyLmpIndexes
    LocationRef:
      type: object
      properties:
        $:
          type: string
          description: Element text value (serialized as "$" in the JSON representation, per observed API responses).
        '@LocId':
          type: integer
        '@LocType':
          type: string
          enum:
          - NETWORK AREA
          - LOAD ZONE
          - NETWORK NODE
          - HUB
          - HUB NODE
          - RELIABILITY REGION
          - EXT. NODE
          - RESERVE ZONE
          - SYSTEM
          - INT. AREA
          - EXT. AREA
          - DISPATCH ZONE
          - CAPACITY ZONE
          - DRRAZ
          - DRR AGGREGATION ZONE
      required:
      - '@LocId'
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_LocationRef
    ServiceInfo:
      type: object
      properties:
        LatestBeginDate:
          type: string
          format: date-time
        CreationDate:
          type: string
          format: date-time
      required:
      - LatestBeginDate
      - CreationDate
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_ServiceInfo
    MonthlyLmpIndex:
      type: object
      properties:
        BeginDate:
          type: string
          format: date-time
        Location:
          $ref: '#/components/schemas/LocationRef'
        DaOnPeakLMP:
          type: number
        DaOffPeakLMP:
          type: number
        DaAverageLMP:
          type: number
        RtOnPeakLMP:
          type: number
        RtOffPeakLMP:
          type: number
        RtAverageLMP:
          type: number
      required:
      - BeginDate
      - Location
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_MonthlyLmpIndex
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: HTTP Basic Authentication over SSL. Credentials come from a free, self-serve ISO Express account; ISO New England states that ISO Express account holders are automatically granted access to the public data feeds. See https://www.iso-ne.com/participate/applications-status-changes/access-software-systems