Environment APIs

Environmental data and weather

15 APIs in this category · last checked 2 October 2026
15
APIs listed
7
need no API key (47%)
4
CORS enabled (27%)
14
HTTPS (93%)

This directory lists 15 environment APIs. 2 of them require no API key and support CORS, so you can call them directly from browser JavaScript with no backend and no sign-up. Every entry shows whether it needs authentication, serves over HTTPS and allows cross-origin requests, so you can pick one that fits your stack before you read a single doc page.

Showing 15 of 15 APIs

BreezoMeter Pollen

Pollen forecasts, plant species breakdown and a daily pollen index for over 65 countries, now served as Google Maps Platform's Pollen API since BreezoMeter was absorbed into Google in 2023.

Auth: apiKey HTTPS CORS: Unknown

Carbon Interface

Converts flights, shipping, electricity use and fuel combustion into estimated CO2 emissions, authenticated with a Bearer API key and a free developer tier before paid usage based plans apply.

Auth: apiKey HTTPS CORS: Yes

IQAir

Real time air quality and weather data from roughly 80,000 stations worldwide, with a free Community plan capped at 500 calls a day and limited to city level AQI for the US and China.

Auth: apiKey HTTPS CORS: Unknown

National Grid ESO

Open electricity system data for Great Britain, now published on the NESO Data Portal after National Grid ESO was renamed the National Energy System Operator, with no key required to read it.

Auth: No HTTPS CORS: Unknown

GrünstromIndex

Quarter hourly green power share of the German electricity grid, published by Next Kraftwerke as a free public feed that needs no signup or API key to read the current index value.

Auth: No HTTPS CORS: Yes

Cloverly

Calculates emissions for an activity and lets you purchase a matching verified carbon offset in the same API call, aimed at checkout and shipping flows, requires an API key to test.

Auth: apiKey HTTPS CORS: Unknown

OpenAQ

Aggregates open air quality measurements such as PM2.5, PM10 and ozone from government and research monitors worldwide, free to use but requires a registered API key sent in the header.

Auth: apiKey HTTPS CORS: Unknown

Climatiq

Turns energy, travel, freight and spend based activity data into CO2e estimates using published emission factors, with a free trial tier available on request and no card needed to start.

Auth: apiKey HTTPS CORS: Yes

UK Carbon Intensity

Forecasts and tracks the carbon intensity of Great Britain's electricity up to two days ahead by region, run by the National Energy System Operator, free with no key and CORS enabled.

Auth: No HTTPS CORS: Yes

Website Carbon

Estimates the CO2 emitted by loading a web page from its transferred bytes and green hosting status, a free public endpoint with no key but no guaranteed uptime or stable response shape.

Auth: No HTTPS CORS: Unknown

Danish Data Service Energi

Open electricity, gas and market data from Denmark's Energinet covering consumption, production and emissions, free to query with no key, rate limits are documented in its own API guide.

Auth: No HTTPS CORS: Unknown

Srp Energy

Unofficial client for Salt River Project's hourly household electricity usage and cost by time of use tier, needs an SRP account login and an xsrf token rather than a simple API key.

Auth: apiKey HTTPS CORS: No

PM2.5 Open Data Portal

Crowdsourced PM2.5 readings from Taiwan's AirBox and LASS sensor networks with national and city level dashboards, documented through a public SwaggerHub reference with no login required.

Auth: No HTTPS CORS: Unknown

PM25.in

Real time air quality readings for Chinese cities including AQI and PM2.5 levels, served over plain HTTP rather than HTTPS and requiring a token obtained by emailing the site owner.

Auth: apiKey HTTPS CORS: Unknown

Luchtmeetnet

Current and forecast air quality component levels for the Netherlands sourced from RIVM measurement stations, a free open API needing no key under the 2020 OpenAPI specification.

Auth: No HTTPS CORS: Unknown

Best Environment and Weather APIs for Developers

An environment API allows developers to integrate weather forecasts, air quality data, climate records, and natural disaster alerts into their applications. These APIs serve outdoor apps, agricultural tools, energy management systems, and smart city platforms.

UK Carbon Intensity and the NESO Data Portal stand out for Great Britain's grid, both free, keyless and CORS enabled. OpenAQ is the best general air quality source, aggregating government monitors worldwide behind a free key, while IQAir adds weather but caps its free tier at city level AQI for the US and China. For emissions accounting, Climatiq and Carbon Interface convert activity data into CO2e estimates, and Cloverly goes further by selling a matching offset in the same call.

The main pitfall here is churn: projects like PVWatts and the original CO2 Offset API have gone dark or been folded into larger platforms, so confirm a domain still resolves first. Regional feeds like Luchtmeetnet suit apps needing just one country.

What to check before you pick one

  • Forecast horizon: Different APIs offer 3-day, 7-day, or 14-day forecasts; choose based on your application's needs.
  • Data resolution: Hyperlocal weather APIs provide grid-level data while global APIs offer city-level resolution.
  • Historical access: Climate analysis and backtesting require APIs with deep historical weather archives.

Frequently Asked Questions

What are environment and weather APIs?

Environment APIs provide programmatic access to weather forecasts, historical climate data, air quality indices, natural disaster alerts, and environmental monitoring data from meteorological services and satellites.

Is OpenWeatherMap API free?

OpenWeatherMap offers a free tier with up to 60 API calls per minute covering current weather, 5-day forecasts, and basic historical data. Hourly forecasts and extended history require paid plans.

How do I get air quality data through an API?

APIs like OpenWeatherMap Air Pollution API and AirVisual provide AQI (Air Quality Index) data by coordinates or city name, including concentrations of CO, NO2, PM2.5, and other pollutants.

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