NFL Media Insider Ian Rapoport reported Sunday that the two sides are closing in on a deal, according to two sources involved in the situation. ESPN first reported the news.
The 49ers viewed retaining the 33-year-old wide receiver as a priority this offseason.
Rapoport reported last week that both sides were amicable about getting a deal done before free agency begins March 11. It appears they are close to accomplishing that goal.
Boldin finished 2013 with 85 receptions for 1,179 yards and seven touchdowns. He was the 49ers' best receiver over the course of the season.
Entering his 12th season, Boldin doesn't need to blow by defenders to be productive, so it's not a surprise his game has aged like a fine wine. He is a big-bodied, physical receiver who provides quarterback Colin Kaepernick a security blanket.