The 49ers have been searching for a suitable backup for Jimmy Garoppolo. Flacco would provide some veteran presence for San Francisco.
Flacco, 35, is a former first-round pick of the Ravens back in 2008. The Broncos agreed to trade a 2019 fourth-round pick to the Ravens for Flacco last year.
Flacco was in the fourth year of a six-year, $125 million contract that contained $44 million guaranteed and set to make a base salary of $20.25 million for 2020 when Denver released him with a failed physical designation last offseason.
He signed a one-year contract worth $1.5 million worth up to $4.5 million with the Jets and is an unrestricted free agent.
In 2020, Flacco appeared in five games and recorded 74 completions on 134 pass attempts (55.2 percent) for 864 yards, six touchdowns, and three interceptions.