GrünstromIndex (Corrently) API

Base URL

https://api.corrently.io/v2.0/gsi

Authentication

No API key for the forecast endpoint under fair use. Corrently sells a paid tier for higher request volumes.

Rate limit

Fair-use policy rather than a published number. Forecasts are hourly — one call per postcode per hour is plenty.

Pricing

Free under fair use; paid plans lift the limits.

CORS

Enabled — callable directly from browser JavaScript

Official docs

Read the docs

Every request below was executed against the live API on 2026-08-21, and the response shown is the real body it returned — not an illustration.

curl 'https://api.corrently.io/v2.0/gsi/prediction?zip=69168'

const res = await fetch("https://api.corrently.io/v2.0/gsi/prediction?zip=69168");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);

import requests

res = requests.get("https://api.corrently.io/v2.0/gsi/prediction?zip=69168", timeout=20)
res.raise_for_status()
print(res.json())

{
  "support": "If you have any question please contact dev@stromdao.com or visit https://premium.corrently.de/",
  "info": "https://corrently.io/books/stromdao-gmbh/page/fair-use-policy",
  "documentation": "https://corrently.io/books/grunstromindex",
  "commercial": "https://corrently.energy/products/corrently-apis-rate-limit-erhohung",
  "signee": "0xE7Fe0626D7B8e3F2e5ECD146F9b11daac1DBE447",
  "forecast": [
    {
      "epochtime": 1787292000,
      "eevalue": 35,
      "ewind": 31,
      "esolar": 7,
      "ensolar": 7,
      "enwind": 31,
      "sci": 29,
      "gsi": 33.25,
      "timeStamp": 1787292000000,
      "energyprice": "-0.0175000",
      "co2_avg": null,
      "co2_g_standard": null,
      "co2_g_oekostrom": 45,
      "timeframe": {
        "start": 1787292000000,
        "end": 1787295600000
      },
      "iat": 1787298371142,
      "zip": "69168",
      "signature": "0x4559f3283cb78723a1bfdb6e099c8bcde11ba6e7b7e73cd18e7719243876549b29071bb06c6f905c8d67524324d5a02aa53514f855840e6bb7c417318972e3421b"
    },
    {
      "epochtime": 1787295600,
      "eevalue": 18,
      "ewind": 9,
      "esolar": 13,
      "ensolar": 13,
      "enwind": 9,
      "sci": 32,
      "gsi": 17.099999999999998,
      "timeStamp": 1787295600000,
      "energyprice": "-0.0090000",
      "co2_avg": null,
      "co2_g_standard": null,
      "co2_g_oekostrom": 55,
      "timeframe": {
        "start": 1787295600000,
        "end": 1787299200000
      },
      "iat": 1787298371143,
      "zip": "69168",
      "signature": "0x57b61e77fb8da8654f49ee512994970c12b06eace6068d29121c297d769

forecastarray

Hourly forecast entries, chronological.

forecast[].gsifloat

GrünstromIndex, 0 to 100. Higher means a greener local mix in that hour.

forecast[].eevalueinteger

Renewable share as a percentage, the simpler cousin of `gsi`.

forecast[].ewind / esolarinteger

Wind and solar contributions to that percentage, so you can see which resource is driving it.

forecast[].enwind / ensolarinteger

Normalised wind and solar values for the same hour.

forecast[].sciinteger

Carbon-intensity score aligned with the Green Software Foundation specification, used by carbon-aware schedulers.

forecast[].co2_g_standard / co2_g_oekostrominteger

Grams of CO2 per kilowatt-hour on a standard versus a green tariff. Either can be null when unavailable.

forecast[].energypricestring

Indicative price as a decimal string. Negative values occur during renewable surpluses.

forecast[].epochtime / timeStampinteger

The hour in Unix seconds and in milliseconds respectively.

forecast[].timeframeobject

Explicit `start` and `end` millisecond bounds for the hour.

signeestring

Blockchain address from Corrently's energy-token work. Not needed for reading the forecast.

support / info / documentation / commercialstring

Contact, fair-use policy, documentation and commercial upgrade links, restated in every response.

• Schedule EV charging or heat pumps for the greenest local hours
• Add carbon-aware timing to a build or batch job running in Germany
• Show households when their regional grid mix is cleanest
• Compare green share against price to see where the two diverge