Real energy bills. Smarter energy use.
Cofy is EnergyID's open-source energy engine for energy communities and suppliers. It calculates complete energy bills for any European tariff, and tells members when to use energy.
What Cofy does
Complete energy bills
The hard part of a bill isn't the energy price. It's the distribution costs, taxes, levies and fees around it, which differ by country, region, grid operator and supplier. Cofy's billing engine handles all of them, for any European country and supplier.
- Supplier47% · € 1,870
- Distribution30% · € 1,200
- Fees and taxes22% · € 880
Energy directives
A simple five-colour signal tells members when to use energy and when to hold off. It can follow forecasts of how much of the community's own production its members will use.
See it at KlimaanOne open energy data API
Members, production, tariffs and time series from sources like EnergyID, ENTSO-E, Elia and NED, in one consistent shape. Communities can be configured in a web console, settings files, or in code.
membersEnergyIDtariffENTSO-E day-aheaddirectiveElia solar forecast
GET /directive/stroomplanner
[{ "timestamp": "2026-10-27T12:00+01:00", "value": "++" }, …]Who uses Cofy
Flemish energy cooperative and supplier. Calculates bills with Cofy, hosted by EnergyID.
Citizen energy association in the Pays de Vilaine, France. Runs Cofy itself.
Dutch energy cooperative. Uses Cofy through EnergyID.
Flemish energy community. Tells households when to use solar power with the Stroomplanner.
Independent by design
Energy is strategic infrastructure, and so is the software that runs it. Cofy keeps that software open, European, and owned by the people who use it.
Open source
- MIT licensed, so anyone can read, audit and run every line.
- Every cost on a bill traces back to a rule you can check.
- No lock-in. The software keeps working whoever hosts it.
European
- Runs on any server, so you can pick your own European hosting provider.
- When EnergyID hosts it for you, it runs on European infrastructure.
- Built and maintained by a team of developers in Antwerp, Belgium.
Cooperative
- Built by EnergyID, a cooperative working on energy data since 2010.
- Co-owned by its employees and by the energy communities and companies it works for.
- So the people who rely on Cofy have a say in where it goes.
Ways to use Cofy
It's the same open-source software in every case, so you can move between them without losing your data or setup.
Hosted by EnergyID
Your own Cofy API, run and kept up to date for you. For suppliers and communities.
Inside EnergyID Advanced
Cofy's data in EnergyID's dashboards, for communities already using EnergyID.
Run it yourself
Free and MIT licensed. For teams that run their own software.
Where Cofy comes from
Cofy is built by EnergyID, which has helped more than 150,000 households and small businesses understand their energy use since 2010.
It started in the Horizon 2020 project REScoop VPP, and is co-funded today by the Interreg North-West Europe project SmartCORE.
