How to Choose the Best Environment API in 2026
There are 17 Environment APIs in our directory. Of these, 7 require no authentication, making them ideal for quick prototyping. 7 are rated beginner-friendly.
Scores last tested: 2026-08-10
Quick Comparison: Top 10 Environment APIs
Ranked by API Score. Measured means we called a real endpoint of that API; Est. means the score is derived from metadata because the endpoint could not be called without credentials. Discontinued APIs are excluded.
| Name | API Score | Auth | HTTPS | CORS | Difficulty |
|---|---|---|---|---|---|
| GrünstromIndex | 96 A+ Measured | No Auth | ✗ | ✓ | Beginner |
| Carbon Interface | 87 A Est. | API Key | ✓ | ✓ | Intermediate |
| Climatiq | 87 A Est. | API Key | ✓ | ✓ | Intermediate |
| PM2.5 Open Data Portal | 87 A Est. | No Auth | ✓ | ? | Beginner |
| Website Carbon | 86 A Measured | No Auth | ✓ | ? | Beginner |
| BreezoMeter Pollen | 82 A Est. | API Key | ✓ | ? | Intermediate |
| CO2 Offset | 82 A Est. | No Auth | ✓ | ? | Beginner |
| Danish data service Energi | 82 A Est. | No Auth | ✓ | ? | Beginner |
| OpenAQ | 72 B Est. | API Key | ✓ | ? | Intermediate |
| PVWatts | 72 B Est. | API Key | ✓ | ? | Intermediate |
Free Environment APIs (No Auth)
These APIs require no API key or signup. Start using them immediately.
CO2 Offset
⭐ Beginner's PickCO2 Offset API calculates and validates the carbon footprint of electricity consumption using the Sustainable Scope 2 framework.
Danish data service Energi
Danish data service Energi provides programmatic access to open energy data from energinet to society via REST API.
GrünstromIndex
⭐ Beginner's PickGrünstromIndex (Green Power Index) provides real-time and forecast data about the proportion of renewable energy in the German electricity grid.
Luchtmeetnet
⭐ Beginner's PickLuchtmeetnet API provides real-time and predicted air quality measurements from the official Dutch national air quality monitoring network (RIVM).
PM2.5 Open Data Portal
⭐ Beginner's PickPM2.5 Open Data Portal provides free access to low-cost PM2.5 (fine particulate matter) sensor data from the LASS community network across Asia, particularly Taiwan.
UK Carbon Intensity
⭐ Beginner's PickThe UK Carbon Intensity API provides official real-time and forecast carbon intensity data for Great Britain's electricity grid, developed by National Grid.
Try It in 5 Minutes: GrünstromIndex
Quick implementation example using GrünstromIndex.
Using curl
curl "https://api.corrently.io/v2.0/gsi/prediction?zip=69168"
JavaScript
const url = "https://api.corrently.io/v2.0/gsi/prediction?zip=69168";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data); New to APIs? Read our Getting Started Guide →
Frequently Asked Questions
How many Environment APIs are available?
There are 17 Environment APIs in our directory as of 2026.
Are there free Environment APIs?
Yes, 7 Environment APIs require no authentication and are completely free to use.
What is the easiest Environment API to use?
GrünstromIndex is one of the easiest to get started with. It is rated as beginner-level and requires no authentication.
Do I need an API key for Environment APIs?
It depends. 7 APIs need no authentication, 9 require an API key, and 0 use OAuth.