There is no legal mixer because the mixing service is based on anonymity, which is something that many governments do not prefer and do not give anyone a license to make tracking money more difficult.

There is a reliable blender/mixer and the reliability comes from that they run a profitable business that makes them not think of scamming you, and therefore the longer the blender is and the fewer technical problems, the better for the average user.

Most of the members here recommend Chipmixer, they have been working since 2017 without any unsolved technical problems.