- https://github.com/public-apis/public-apis (A collective list of free APIs)
- https://github.com/n0shake/Public-APIs
- https://github.com/toddmotto/public-apis (huge list of public APIs)
- http://openweathermap.org
- https://market.mashape.com
- http://numbersapi.com (An API for interesting facts about numbers)
- http://fixer.io (JSON API for foreign exchange rates and currency conversion)
- http://restcountries.eu (Get information about countries)
- http://open-notify.org (Open APIs From Space)
- https://github.com/toddmotto/public-apis
- http://swapi.co
- http://jsonplaceholder.typicode.com
- https://www.themoviedb.org/documentation/api
- http://forismatic.com/en/api
- https://randomuser.me
- https://freegeoip.net
- https://dog.ceo/dog-api
- https://uinames.com
- https://github.com/APIs-guru/graphql-apis
- https://open-platform.theguardian.com
- https://developer.nytimes.com
- https://currentsapi.services
- https://github.com/HackerNews/API
- https://github.com/public-apis/public-apis
- https://github.com/fawazahmed0/exchange-api
- http://sheetsu.com/ (Turn a Google Spreadsheet into an API)
- http://www.json-generator.com/
- https://github.com/typicode/json-server
- https://github.com/jeffknupp/sandman2
- https://github.com/wprl/baucis
- https://jsonbin.io/
- http://www.nodaljs.com/
- https://www.firebase.com/
- http://httpbin.org/
- https://jsonplaceholder.typicode.com/ Fake Online REST API for Testing and Prototyping
Disclaimer: Am the developer of the website.
You can add https://jsonbin.io to this list. It's a free JSON Storage service.