Florida cornerback Teez Tabor, Iowa tight end George Kittle also visited the team on Wednesday, and UConn safety Obi Melifonwu met with the 49ers on Tuesday, according to the report.
Wednesday was the final day in which NFL teams could host 2017 NFL Draft prospects for an official visit.
Fournette is rated the No. 1 running back in the draft by NFL Network draft expert Mike Mayock, while Peppers and Melifonwu are his No. 3 and 4 safeties, respectively. Kittle is tied for fifth at his position in Mayock's rankings, and Tabor has seen his stock take a hit due to his slow 40-yard dash times.
San Francisco holds the No. 2 overall pick in next week's draft (April 27-29 in Philadelphia).
Most NFL.com mock drafts project the 49ers to take Stanford's Solomon Thomas with the No. 2 pick, but there's been buzz that the club would love to trade down in Round 1 -- 49ers general manager John Lynch has said he's "open for business" when it comes to taking calls from teams interested in the pick.
If Lynch doesn't take Fournette at No. 2, the star running back isn't likely to last much longer. All of the most recent NFL.com mock drafts have Fournette going to the Jaguars two picks later at No. 4.