A person who sells files is typically referred to as a "file vendor" or a "file seller." In the digital realm, they may also be called a "digital content provider" or a "digital file merchant." The specific term used can vary depending on the context and the type of files being sold.
An author is a person who writes and sells books.
The person who sells drink is known as sellsmen
baker
You call a person who sells flowers a (Florist)
A bookie. Droll. You could call that person a bookseller or shopkeeper.
A person who sells ship supplies is called a chandler
fishmonger
A chandler.
A florist.
A butcher.
jeweler
A "Shipbroker".