Open Library
An open catalog of every book.
APIsFree· OSSNo ratings
#Open Data
Sites tagged with Open Data.
NASA Open APIs
Space data, free from NASA.
APIsFreeNo ratings
Public APIs
The famous list of free APIs.
APIsFree· OSSNo ratings
REST Countries
Country data via REST.
APIsFree· OSSNo ratings
Frankfurter
Free currency exchange rates API.
APIsFree· OSSNo ratings
Open-Meteo
Free weather API, no key needed.
APIsFreemium· OSSNo ratings
PokéAPI
All Pokémon data, RESTfully.
APIsFree· OSSNo ratings