confirmer
/kənˈfɜr.mər/Definitions
1. noun
One that confirms, especially a person who verifies the authenticity of something
“The notary public acted as a confirmer of the couple’s signatures.”
2. noun
A person who confirms or agrees with something
“The confirmer of the business plan was instrumental in securing the initial funding.”
3. verb
to confirm or verify something
“The company will confirmer the new policy before releasing it to the public.”