There is a confusion between "royalty free music" and "free music", "royalty free music" means that you can buy a license one time, and you can use the music in your video without having to pay royalties every year. "Free Music" is a music you can (in some cases) use for free.
If you are looking for FREE royalty free music, you can find some music libraries in the internet that offers some tracks for free. You can also visit the Music Screen Library, the use of all the tracks is free for students, humanitarian organizations and particulars, try it here: Musicscreen.org
I vote for TunePocket here. It's a relatively small catalog but well curated.
You get unlimited access and their subscription fee is like $99 per year for individuals (more for businesses).
With AudioJungle or Pond5 that will only get you 3 - 5 tracks or even less if you need extended license. With TunePocket you can have as many as you need.
I agree, TunePocket is a great site !
Well, maybe I'm a little late, but watching this thread I wanted to say that there is also music with creative commons licenses which you can use the same way as stock music because it's royalty-free and without copyright. Yeah, I know usually these alternative places haven't so much variety, but what if you find what you look for? For example https://patrickdearteaga.com/royalty-free-music/
If you're a member of Envato elements, They're just added Music for there monthly subscription users.
Envato own AudioJungle and will probably be offering some of the licences available on AudioJungle on the elements equivalent - Like they do with graphics etc.
in addition to that royalty-free and free music issue, you should also be aware that there is a difference between PRO free music and PRO music.
Royalty free music does not mean the music is also PRO free = it can happen that you have to pay money to performing rights organizations such as PRS/MCPS, GEMA, BMI etc.
You should really stick to libraries that are curated and where you get support when needed.
I can recommend Musicbed or SmartSound - SmartSound is even royalty free and offers adaptive music, it's a huge time saver.
Think they have a Black Friday special for their Software SOncfire Pro 6 running at the moment!