The API uses two methods outlined by the IPCC, DEFRA U.K & GHG Protocol. https://www.notion.so/Trip-to-Carbon-Calculations-Info-e8d5e1bf80d647f09bfce784c19a5423
The free API has a rate limit of about 5 requests per minute. Authenticated requests using API keys have a higher limit of 20 requests/min. The self-hosted APIs will not have one set by Trip to Carbon.
The API is free to use at the current rate limits. Trip to Carbon will soon have a new open model that allows people to self-host the API and other tools (thus, you decide the limit). Sign up to the newsletter to be updated when this is launched!
The API can be used for a range of things. Examples: Calculating personal/business emissions or Integrating into travel sites
You can send an email here: firstname.lastname@example.org
Trip to Carbon's API cannot be accessed from client side scripts. To get around this we suggest using a proxy server to make requests to the API from you client side script/application