Spillman, who was among the 49ers' cuts Saturday when the team turned in its initial 53-man roster, had been with San Francisco since 2010.
By parting with Spillman, also a backup safety, San Francisco saved $1.25 million in salary; he also had a salary cap number of almost $1.56 million, per ESPN Stats & Info.
Three other players the 49ers cut Saturday have reportedly found homes elsewhere in cornerback Darryl Morris (Houston Texans), running back Glenn Winston (Cleveland Browns) and guard Ryan Seymour (Browns).
The 49ers' special teams took a hit with the cuts. Not only are Spillman, who led special teams with 19 tackles, and Morris gone, but so too are receiver Kassim Osgood and safety Bubba Ventrone. It is thought Osgood could re-sign with the team after Week 1 as his salary of $955,000 will no longer be fully guaranteed.
"There are young players that are going to have to rise to the challenge," coach Jim Harbaiugh said Saturday. "It'll be a challenge for our whole football team -- the veteran players, young players, to get our special teams where we're used to them being."