I have been working professionally as a mastering engineer since the year 2000.
If you have music that you want to have mastered, Sofia and I will be glad to help you over at Stockholm Mastering.
If you are interested in learning more about mastering, please have a look at our other site Mastering Explained, where we teach mastering through blog posts, videos, and courses.
We also have a YouTube channel where we teach mastering. Have a look!