Forex Brokers List

No.
An STP broker uses Market execution only.
This is due to the fact that STP brokers are not counterparties, have No Dealing Desk, and thus cannot instantly fill in Client's orders.

Instead, they send orders to their liquidity provider(s), where it's executed. The time it takes to reach the liquidity provider (although it takes only milliseconds) and get an "OK" for an order, makes it impossible to have an Instant fill at the initially requested price.