Is Endianness Unity platform independent

Does all of builds will be little endian format regardless of the final build platform?

I'd rather not use BitConverter class with:

 if (BitConverter.IsLittleEndian)
     Array.Reverse(bytes);

If it will be little endian anyway, creating, checking and reversing after is a waste of resources. I already build my custom byte converter class which threats everything as little endian. But the question about multiplatform stays.