I would second @Seth Dingle suggestions although personally I don't use barchart, the other two definitely.
Although not for extracting and manipulating, but access to Bloombergesque data I can highly recommend Koyfin. Most other data sites concentrate on equities. Koyfin has that plus rates, commodities, currencies etc globally not just US centric. Also you can build your own dashboard for quick looks.
As you highlighted regards data access. If you are charging someone 2&20 to invest their money you can't be making decisions based on data the plebs can access ;) Many use proprietary data gained from source.