At its peak, Forex Tester 2 was praised for its simplicity and robustness. What is Forex Trading & How Does it Work - BofA Securities

Most traders spend 90% of their time looking for a "signal" and 0% of their time verifying if that signal actually works.

Because the data is static, you can replay the exact same 6-month period 50 times. Did your breakout strategy fail last time? Change one rule—the stop loss distance, the moving average period, or the entry time—and run the period again. This is impossible in live markets, where conditions are never identical twice.