Carbon Emissions APIs
Carbon emission APIs either estimate CO2 for an activity or report how clean the grid is. Carbon Interface calculates emissions from electricity, flights, vehicles and fuel, and SustainMetrics exposes GHG emission factors from DEFRA, EPA, ADEME and Ember for Scope 1-3 reporting. The UK Carbon Intensity API gives half-hourly figures for Great Britain's grid, and the free Website Carbon API rates a single webpage. Free Weather APIs →
| API | Pricing | Auth | Format | Free tier | Status |
|---|---|---|---|---|---|
Carbon InterfaceEstimates CO2 emissions from electricity, flights, vehicles, shipping and fuel via REST. Weather & Environment › Climate & Carbon | Freemium | API key | JSON | <100/day | Live |
SustainMetrics18,000+ GHG emission factors from DEFRA, EPA, ADEME and Ember for Scope 1-3 carbon footprint calculations. Weather & Environment › Climate & Carbon | Freemium | API key | JSON | <100/day | Live |
UK Carbon Intensity APIHalf-hourly forecast and actual carbon intensity of Great Britain's electricity grid, national and regional. Weather & Environment › Energy | None | JSON | Unlimited | Live | |
Website Carbon APIEstimates a webpage's CO2 emissions and carbon rating from its transfer size and hosting type. Weather & Environment › Climate & Carbon | Free | None | JSON | Unlimited | Live |
Carbon InterfaceFreemiumLive
Estimates CO2 emissions from electricity, flights, vehicles, shipping and fuel via REST.
API key · JSON
<100/day
no machine-readable spec
SustainMetricsFreemiumLive
18,000+ GHG emission factors from DEFRA, EPA, ADEME and Ember for Scope 1-3 carbon footprint calculations.
API key · JSON
<100/day
no machine-readable spec
UK Carbon Intensity APILive
Half-hourly forecast and actual carbon intensity of Great Britain's electricity grid, national and regional.
None · JSON
Unlimited
no machine-readable spec
Website Carbon APIFreeLive
Estimates a webpage's CO2 emissions and carbon rating from its transfer size and hosting type.
None · JSON
Unlimited
no machine-readable spec
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Choosing a Carbon Emissions API
Is there a free Carbon Emissions API?
Yes. Website Carbon API is free to use, and Carbon Interface and SustainMetrics have a free tier alongside paid plans. See all free Weather APIs.
Which Carbon Emissions APIs work without an API key?
UK Carbon Intensity API and Website Carbon API need no key or sign-up, so you can try them with a plain request.
Can I call a Carbon Emissions API from front-end JavaScript?
UK Carbon Intensity API allows cross-origin requests and needs no key, so it works straight from the browser. For the others, call them from your server so your key stays private.
Broader: Climate & Carbon APIs · Weather & Environment APIs