Access to Open Data from Governments, Non-profits and NGOs around the world.
Socrata API is a free Open Data API that requires OAuth authentication, is served over HTTPS and supports CORS, so it can be called from the browser.
Details from dev.socrata.com.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
VPS and cloud server prices from 46 providers, read daily from their own pricing pages and APIs
Economic data for 218 countries — GDP, population, inflation, and 440+ indicators from IMF and World Bank
The Socrata API is provided by Socrata (dev.socrata.com).
Yes. The Socrata API is listed in the Open Data category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The Socrata API uses OAuth authentication, so you need to register for credentials before making requests.
Yes. The Socrata API supports CORS, so front-end JavaScript can call it directly.
Yes. The Socrata API is served over HTTPS, so it's safe to use in production.