Freesound Forums

All the sounds of his site are free to comercial?

All sounds can be used for commercial projects except those that have the "Attribution Non-Commercial" license (which is a a fair few sounds, but most are either CC0 or Attribution which can be used commercially).

You can check what license a sound has by looking just below its download button, and you can filter your sound search by license to exclude the "Attribution Non-Commercial" sounds.

You can read a little more about each of the licenses here:

https://freesound.org/help/faq/#licenses