Hi,

> Why is Forex Strategy Builder free?

That is my will. Of course, if you fill uncomfortable using it for free, you can donate.

> Do I need to use a specific broker?

No, you don't. FSB is not a trading platform. It is a strategy development and research tool. These strategies can work with all brokers on all markets.

> What is the source of the spot rate data?

The distributed data are from a Bulgarian broker.
It is better to use data from your broker. (See the help for details.)

P.S.
Please use the forum. I'm receiving 100 emails daily.

Regards,
Miroslav Popov