Shortcut:
Scratch is free (meaning that no money needs to be paid to use it), has always been free, and will always be free. This is made possible by donations to the Scratch Foundation.[1] Donation is optional, and the donation banner can be seen in the Front Page.

Scratch is also free in the meaning of free/open-source software, as its code is publicly available under an open-source license. The source code can be found on GitHub.

References

  1. "Scratch is and always will be free. You don’t need a license to use Scratch in your school, home, or anywhere else. The development and maintenance of Scratch is paid for by grants and donations." scratch:faq