Skyscanner Flight Search is the most popular API, followed by Open Weather Map and API-FOOTBALL. The top 50 most popular APIs on RapidAPI include Skyscanner Flight Search, Open Weather Map, API-FOOTBALL, The Cocktail DB, REST Countries v1, Yahoo Finance, Love Calculator, URL Shortener Service, NasaAPI, Numbers, musiXmatch, SYSTRAN.io – Translation and NLP, Chuck Norris, Hearthstone, Currency Exchange, Breaking News, Booking, Free NBA, Deezer, Email Validator, Urban Dictionary, Pokemon Go, Recipe – Food – Nutrition, Investors Exchange (IEX) Trading, Movie Database (IMDB Alternative), webcams.travel, City Geo-Location Lookup, Temp Mail, uNoGS, WordsAPI, GeoDB Cities, Crime Data, Kajak, Chicken Coop, Joke, OpenAPI 1.2, Text-to-Speech, vin-decoder, Cricket Live Scores, Youtube To Mp3 Download, Web Search, JokeAPI, Genius, Nexmo SMS Messaging API, Currency Converter, TheRundown, BrainShop.AI, Utelly, Flight Data, Crypto Asset Tickers, Skyscanner Flight Search, Recipe – Food – Nutrition, API-FOOTBALL, Open Weather Map, and Hearthstone. Most of these APIs are free to use, with some offering paid pricing plans for increased usage.