IEX Cloud
Realtime & Historical Stock and Market Data
Spreadbetting and CFD Market Data.
IG API is a free Finance API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
How to get access to IG's platform and APIs, so you can start coding as quickly as possible.
Details from labs.ig.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.
Realtime & Historical Stock and Market Data
Get complete history of India Mutual Funds Data
The IG API is provided by IG Labs (labs.ig.com). How to get access to IG's platform and APIs, so you can start coding as quickly as possible.
Yes. The IG 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 IG API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the IG API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The IG API is served over HTTPS, so it's safe to use in production.