This applies only if you want to self-host Khofly API.

If OPEN_WEATHER_API_KEY is set in API .env it will use OpenWeatherMap API otherwise it will default to Open Meteo.

OpenWeatherMap One Call API is used to fetch data server side. One Call API requires an API key to be used so if you want to self host the Khofly API you'll need to go to this link and subscribe to get your key, then just add it to the API .env file.

One Call API is "pay as you call" but you still get 1000 free requests per day and you can set a limit to how many requests are allowed in the dashboard so you can ensure that you don't go over the 1000 requests if you don't want to pay anything.

Open Meteo provides a free API for non-commercial use. The data might be slightly different than what OpenWeatherMap provides, but you can use whatever is most accurate for your area.