Alpha Vantage API showed inaccurate results from time to time and their customer support is nonexistent.

I've noticed the same thing with Alpha Vantage, but I switched to Alpha Vantage because Yahoo turned off their public API. It's the Yahoo API available again now?

They have an undocumented one that you can check in the network tab on your browser. this is how the API looks like https://query1.finance.yahoo.com/v8/finance/chart/%5EGSPC?in...

We've had the paid plan with "premium" support. Inexistent and borderline rude. We just moved to IEX cloud for data (proper documentation, sandbox, etc).

I'm using it in a project with the yfinance python module.