An open-source Green Button (NAESB ESPI) third-party application that bridges utility energy data into Home Assistant.
The hosted server is a stateless OAuth proxy: utilities require a stable public callback URL, but your data never lives on our server. Refresh tokens are stored encrypted on your Home Assistant instance, and every request flows through the proxy carrying the token from your side.
🚧 Pre-alpha. Burlington Hydro (Ontario, Canada) is the first targeted utility. See the implementation plan in docs/ for the phased roadmap.
server/— Kotlin/Ktor proxy server (deployed to Fly.io with scale-to-zero)docs/— Architecture, deployment, per-utility notesbranding/— Logo and brand assets
The Home Assistant custom integration lives in its own repository so HACS validation finds the canonical custom_components/ + hacs.json layout at the repo root: rocketraman/open-green-button-homeassistant.
The hosted server holds no per-user durable state. Per-utility OAuth client credentials are configured globally; every other piece of state (your refresh token, your usage data) lives only on your Home Assistant instance.
Open Green Button is free to use. If it saves you time or you'd like to help keep it maintained and hosted (there's a small Fly.io bill and ongoing time spent adding new utilities and keeping up with Home Assistant changes), donations are welcome.
Suggested: $5 / month — roughly enough to cover hosting plus a contribution toward maintenance time. Anything above that funds new utility integrations.