I use Alpha Vantage, just for a personal (1 user, me) application. The service is free, you just need an API key. - https://www.alphavantage.co/

https://www.alphavantage.co/support/#api-key "While we are proud to provide free API service with no daily/weekly/monthly call limits, we recommend that API call frequency does not extend far beyond ~100 calls per minute so that we can continue to deliver the optimal server-side performance. If you would like to target a much larger API call volume, please drop us a note..."