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