These are a couple freebies I use but don't often mention in our posts.
One of the FWIW things I notice on the forum is that a lot of members take the old school "loud is better" approach to their mix downs. Of all the major streaming platforms SoundCloud is the only on that lets you get away with this. ALL of the others will reduce your volume and possibly introduce artifacts doing so. Given the state of my hearing (need to avoid anything over 80 db) I have to be very careful when listening to songs on the User Forum as some are exponentially louder than others - something that would not happen listening on Spotify, Apple, YouTube, etc. So ...
Here a great free plug in that makes it very easy to set your limiter at the desired 12-14 LUFS ... assuming you are interesting in the streaming platforms, etc.
https://youlean.co/youlean-loudness-meter/And here is a link to a website that lets you drop your song on it (without actually uploading it) and it will then inform you how much the different streaming platforms would reduce or raise the volume of your production.
https://www.loudnesspenalty.comEven if you don't submit your tunes for streaming you might find them of interest ... particularly the second one.
Bud