The music and lyrics are in the public domain in the European Union and the United States. The copyright expired in the European Union on January 1, 2017. A U.S. federal court ruled in 2016 that Warner and Chappell’s copyright claim was invalid and there was no other claim to copyright.
Except it is not copyrighted anynore
From Wikipedia https://en.wikipedia.org/wiki/Happy_Birthday_to_You