Problem

Some brokers like FXCM and OANDA provide their own APIs for data feed and execution. But most CFD brokers — IC Markets, Vantage, Pepperstone — have no manager API. You cannot programmatically get price data or execute trades through a REST endpoint. Third-party data APIs like Polygon or Twelve Data give you generic aggregated prices, but those are not the prices your broker quotes. The spread, the slippage, the exact tick — they differ between brokers. If your strategy backtests on Polygon data but executes on IC Markets prices, the results will not match.