aid: hydro-one url: https://raw.githubusercontent.com/api-evangelist/hydro-one/refs/heads/main/apis.yml name: Hydro One kind: company description: >- Hydro One Limited (TSX: H) is Canada's largest electricity transmission and distribution service provider, transmitting and distributing electricity across Ontario — the province the company describes as "home to 38 per cent of Canada's population." It sits in the regulated wires tier of the value chain: it owns and operates the provincial transmission grid and a rural/regional distribution network serving roughly 1.5 million customers, while the Ontario market itself is operated by the IESO and rates are set by the Ontario Energy Board. Its API posture is defined entirely by regulation, not by product. Ontario Regulation 633/21 (Energy Data, under the Electricity Act, 1998) compels Ontario electricity and natural gas distributors to implement Green Button Download My Data (DMD) and Connect My Data (CMD) and to have those implementations certified by the Green Button Alliance. Hydro One publishes DMD as an authenticated XML export inside My Account, runs a live Green Button CMD OAuth 2.0 authorization surface at www.hydroone.com/green-button-cmd-home, and operates a published third-party vendor onboarding form and terms and conditions — but the CMD resource base URI, client credentials, and test accounts are issued privately during onboarding and are not published anywhere. There is no developer subdomain, no OpenAPI or Swagger definition, and no self-serve signup. The split is the finding: consumer energy data is available through a real, standards-based, mandated API that a developer can only reach by application and 90-day connectivity testing, while open grid and market data is entirely absent — Hydro One publishes no open data portal and no documented public system or outage API, leaving Ontario market data to the IESO. accessModel: pricing: free onboarding: application-approval trial: false try_now: false public: false label: Free · Application and approval required confidence: high source: - documentation - terms generated: '2026-07-27' method: manual image: https://www.hydroone.com/Style%20Library/H1/images/logo.svg tags: - Energy - Canada - Utilities - Electricity - Grid - Smart Metering - Green Button - Energy Data - Transmission - Distribution created: '2026-07-27' modified: '2026-07-27' specificationVersion: '0.19' apis: - aid: hydro-one:hydro-one-green-button-connect-my-data name: Hydro One Green Button Connect My Data (CMD) description: >- Hydro One's Green Button Connect My Data implementation, mandated by Ontario Regulation 633/21. A registered third-party vendor obtains an OAuth 2.0 authorization code after the customer authenticates with Hydro One and consents, then retrieves that customer's electricity usage and billing data as NAESB ESPI XML. The live authorization surface at https://www.hydroone.com/green-button-cmd-home was observed serving a real Green Button authorization request carrying ESPI function-block scope syntax (FB=1_3_4_5_13_15_16_31_37_39_51_53_54_55_56_57_58_59_60_64_65;historyLength=32148000) for a third-party redirect URI. Hydro One does not publish the CMD resource base URI, an OpenAPI definition, or any endpoint reference — Client ID, Client Secret, test accounts, and URI(s) are issued privately during vendor onboarding, followed by a 90-day connectivity test and an exchange of RSA 2048-bit certificates over TLS. humanURL: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-apps tags: - Green Button - Connect My Data - ESPI - Energy Data - OAuth2 - Consumer Data properties: - type: Documentation url: https://www.hydroone.com/saving-money-and-energy/green-button - type: Documentation url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-apps - type: TermsOfService url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-terms-and-conditions - type: SignUp url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-onboarding-form - type: GettingStarted url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-apps - type: Authentication url: https://www.hydroone.com/green-button-cmd-home - type: Authentication url: authentication/hydro-one-authentication.yml - type: OAuthScopes url: scopes/hydro-one-scopes.yml - type: Sandbox url: sandbox/hydro-one-sandbox.yml - type: Regulation url: https://www.ontario.ca/laws/regulation/210633 - type: Standard url: https://www.greenbuttonalliance.org/ - type: Regulator url: https://www.oeb.ca/consumer-information-and-protection/green-button common: - type: DomainSecurity url: security/hydro-one-domain-security.yml - type: Authentication url: authentication/hydro-one-authentication.yml - type: OAuthScopes url: scopes/hydro-one-scopes.yml - type: Conventions url: conventions/hydro-one-conventions.yml - type: Conformance url: conformance/hydro-one-conformance.yml - type: Lifecycle url: lifecycle/hydro-one-lifecycle.yml - type: Sandbox url: sandbox/hydro-one-sandbox.yml - type: LLMsTxt url: llms/hydro-one-llms.txt - type: Website url: https://www.hydroone.com/ - type: About url: https://www.hydroone.com/about - type: Documentation url: https://www.hydroone.com/saving-money-and-energy/green-button - type: GettingStarted url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-apps - type: SignUp url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-onboarding-form - type: TermsOfService url: https://www.hydroone.com/saving-money-and-energy/green-button/third-party-terms-and-conditions - type: TermsOfUse url: https://www.hydroone.com/terms-of-use - type: PrivacyPolicy url: https://www.hydroone.com/privacy - type: Support url: https://www.hydroone.com/contact - type: News url: https://www.hydroone.com/newsroom - type: LinkedIn url: https://www.linkedin.com/company/hydro-one - type: Regulator url: https://www.oeb.ca/consumer-information-and-protection/green-button maintainers: - FN: Kin Lane email: kin@apievangelist.com