https://www.freepublicapis.com/
- 224+ APIs
- tested daily
https://github.com/public-apis/public-apis
Animals Anime Anti-Malware Art & Design Authentication & Authorization Blockchain Books Business Calendar Cloud Storage & File Sharing Continuous Integration Cryptocurrency Currency Exchange Data Validation Development Dictionaries Documents & Productivity Email Entertainment Environment Events Finance Food & Drink Games & Comics Geocoding Government Health Jobs Machine Learning Music News Open Data Open Source Projects Patent Personality Phone Photography Programming Science & Math Security Shopping Social Sports & Fitness Test Data Text Analysis Tracking Transportation URL Shorteners Vehicle Video Weather
https://mixedanalytics.com/blog/list-actually-free-open-no-auth-needed-apis/
- including weather / METAR
- useful for flight sim