Quandl

Quandl (acquired by Nasdaq in 2018) is a leading provider of financial, economic and alternative data. It sources data from over 350 publishers and delivers it through an API to investment professionals across various domains such as hedge funds, investment banks and other financial institutions. Quandl's offerings include core financial data like stock prices, exchange rates, and economic indicators as well as unique alternative datasets like corporate aviation data, satellite imagery analysis, online consumer behavior data among others. As of early 2017, Quandl had over 200,000 users and facilitated 10 million daily data downloads. Though it provides some free datasets, much of its data is subscription-based with paid access.

Quandl allows publishers to monetize their data by uploading it to the platform and setting the terms of access for customers. Customers can access this data through Quandl's API and utilize programming tools across R, Python, Excel and others to conduct analysis. The company also offers tools like Nasdaq Analytics Hub that combine its alternative and core data to help generate alpha and provide investing insights.