Q: Is it ok to use a different brand of developer than the brand of the actual hair color?
A: Yes. As long as the developer is intended for the type of hair color you are using (demi-permanent & semi-permanent versus permanent color) you can interchange brands if you need to do so.
However, you should keep in mind that any guarantees offered by the makers of the color formula you are using are likely to be invalidated unless you use the manufacturer’s developer as well.
The reason for the exclusivity between semi-/demi-permanent color and permanent color is that the non-permanent colors use a milder developer formula strictly to provide deposit of color only.
When a non-permanent color is used with a developer that is too strong, one of the negative outcomes is that the color mix can lighten the starting color and the color that is deposited doesn’t give the
expected result. The resulting color can fade, quickly revealing that lightening and leave the hair looking unpleasant.