I use OpenWeatherMap. Which has a pretty great free tier. Many APIs are "free" at least to some level, though if you are hoping to pack the API key in an app yo

I use OpenWeatherMap. Which has a pretty great free tier. Many APIs are "free" at least to some level, though if you are hoping to pack the API key in an app you ship to millions of people, expect to pay for it. APIs cost money and server resources to run, the free lunch is only ever going to extend to a certain amount of use.