M
API Matrix

GrünstromIndex API

⭐ Beginner's Pick Environment / No Auth Required Beginner HTTP CORS
Free to Use Varies (check documentation)
72 Score
Grade B
Visit Official Site Compare Alternatives

Overview

GrünstromIndex (Green Power Index) provides real-time and forecast data about the proportion of renewable energy in the German electricity grid. It is completely free with no API key required and returns a simple score between 0 and 100 for any German postal code. Developers can use it to schedule energy-intensive tasks during greener grid periods.

💡

Beginner Tip

No sign-up needed — just query by German zip code to get a green energy score from 0 (very dirty grid) to 100 (fully renewable). Use the forecast endpoint to find the greenest time window for running energy-intensive jobs.

Available Data

GrünstromIndex data via REST API
JSON-formatted response data
Freely accessible without authentication

Example Response

JSON Response 
{
  "status": "success",
  "data": {
    "result": "Data from GrünstromIndex",
    "description": "Green Power Index for Germany (Grünstromindex/GSI)",
    "timestamp": "2025-01-15T10:00:00Z"
  }
}

Field Reference

gsi Green Power Index score from 0 to 100; higher values mean more renewable energy in the local grid
timeStamp Unix timestamp (milliseconds) for the forecast data point
zip The German postal code for which the green energy data is calculated
renewable Percentage of renewable energy sources in the grid mix at the given time

Implementation Example 

const url = "https://gruenstromindex.de/";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

Empty array in response The zip code is not recognized or outside Germany
✓ Use a valid 5-digit German postal code; this API only covers the German electricity grid
CORS error in browser Some browser environments restrict cross-origin requests to this API
✓ Make requests from a backend server rather than directly from client-side JavaScript in browsers
404 Not Found Incorrect endpoint URL path used
✓ Use the correct base URL: https://api.corrently.io/v2.0/gsi/prediction with the zip query parameter

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 10/20
🔒 Security 5/15
🛠 Developer XP 20/20
✓ Reliability 7/15
Response Time 783ms

Fully tested on Apr 5, 2026

Technical Specifications

Auth No Auth
HTTPS NO
CORS YES
Category Environment
Difficulty Beginner
Verified: 2026-04-04

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