Public API Database

OpenWeatherMap is an online service that provides a free API for weather data, including current weather data, forecasts, and historical data to the developers of web services and mobile applications.

Fixer.io is a free JSON API for current and historical foreign exchange rates published by the European Central Bank.

World Bank offers an API to access their Indicators, Projects and Financial Data

Reddit is a popular news site and offers an API to access their vast amounts of user generated content. Most normal, human visitable URLs can be made into usable JSON endpoints simply by adding .json to the end of them.

Random quotes pulled from the Ron Swanson quote database.

Investment data and other company information as a service.

Live updates on geographic events such as earthquakes.