Real-Time, Intraday & Historical Market Data, News and Sentiment API.
StockData API is a free Finance API that requires apiKey authentication, is served over HTTPS and supports CORS, so it can be called from the browser.
StockData.org - free intraday and historical stock, forex and crypto data and news in JSON format with easy to use API endpoints. Sign up for free.
Details from stockdata.org.

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.
SEC filings, financial statements, earnings, ETF holdings and ownership data
The StockData API is provided by StockData (stockdata.org). StockData.org - free intraday and historical stock, forex and crypto data and news in JSON format with easy to use API endpoints. Sign up for free.
Yes. The StockData API is listed in the Finance 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 StockData API uses apiKey authentication, so you need to register for credentials before making requests.
Yes. The StockData API supports CORS, so front-end JavaScript can call it directly.
Yes. The StockData API is served over HTTPS, so it's safe to use in production.