ISO New England Monthlyper API

openapi: 3.2.0
info:
  title: ISO New England Web Services API v1.1 Monthlyper 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: monthlyper
  description: 5 path template(s) under /monthlyper in the published ISO New England Web Services API v1.1 documentation.
paths:
  /monthlyper:
    get:
      operationId: getMonthlyper
      summary: Default resource
      description: Default resource. Redirects to MonthlyPER Info.
      tags:
      - monthlyper
      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.monthlyper.html
        harvested: '2026-07-27'
  /monthlyper/current:
    get:
      operationId: getMonthlyperCurrent
      summary: Get the current MonthlyPER
      description: Get the current MonthlyPER.
      tags:
      - monthlyper
      responses:
        '200':
          description: a MonthlyPERElement containing the current MonthlyPER.
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/MonthlyPeakEnergyRents'
            application/json:
              schema:
                $ref: '#/components/schemas/MonthlyPeakEnergyRents'
        '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.monthlyper.current.html
        harvested: '2026-07-27'
      x-xml-element: MonthlyPeakEnergyRents
  /monthlyper/info:
    get:
      operationId: getMonthlyperInfo
      summary: Get the Service Info for MonthlyPER
      description: Get the Service Info for MonthlyPER.
      tags:
      - monthlyper
      responses:
        '200':
          description: the ServiceInfoElement for MonthlyPER.
          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.monthlyper.info.html
        harvested: '2026-07-27'
      x-xml-element: ServiceInfo
  /monthlyper/month/{month}:
    get:
      operationId: getMonthlyperMonthByMonth
      summary: Get an entire months MonthlyPERs
      description: Get an entire months MonthlyPERs.Only the past 30 days
      tags:
      - monthlyper
      responses:
        '200':
          description: a MonthlyPERsElement containing the MonthlyPERs.
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/MonthlyPeakEnergyRents'
            application/json:
              schema:
                $ref: '#/components/schemas/MonthlyPeakEnergyRents'
        '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.monthlyper.month.month.html
        harvested: '2026-07-27'
      x-xml-element: MonthlyPeakEnergyRents
      parameters:
      - name: month
        in: path
        required: true
        schema:
          type: string
        description: The month to retrieve data for (YYYYMM)
  /monthlyper/month/{month}/capacityZone/{capacityZoneId}:
    get:
      operationId: getMonthlyperMonthByMonthCapacityZoneByCapacityZoneId
      summary: Get an entire months HourlyPERs
      description: Get an entire months HourlyPERs.Only the past 30 days
      tags:
      - monthlyper
      responses:
        '200':
          description: a HourlyPERsElement containing the HourlyPERs.
          content:
            application/xml:
              schema:
                $ref: '#/components/schemas/MonthlyPeakEnergyRents'
            application/json:
              schema:
                $ref: '#/components/schemas/MonthlyPeakEnergyRents'
        '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.monthlyper.month.month.capacityZone.capacityZoneId.html
        harvested: '2026-07-27'
      x-xml-element: MonthlyPeakEnergyRents
      parameters:
      - name: month
        in: path
        required: true
        schema:
          type: string
        description: The month to retrieve data for (YYYYMM)
      - name: capacityZoneId
        in: path
        required: true
        schema:
          type: string
components:
  schemas:
    CapacityRef:
      type: object
      properties:
        $:
          type: string
          description: Element text value (serialized as "$" in the JSON representation, per observed API responses).
        '@CapacityZoneId':
          type: integer
      required:
      - '@CapacityZoneId'
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_CapacityRef
    MonthlyPeakEnergyRent:
      type: object
      properties:
        BeginDate:
          type: string
          format: date-time
        Location:
          $ref: '#/components/schemas/CapacityRef'
        MonthlyPER:
          type: number
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_MonthlyPeakEnergyRent
    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
    MonthlyPeakEnergyRents:
      type: object
      properties:
        MonthlyPeakEnergyRent:
          type: array
          items:
            $ref: '#/components/schemas/MonthlyPeakEnergyRent'
      x-xsd-source: schemas/iso-new-england-web-services-ns0.xsd#type_MonthlyPeakEnergyRents
  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