Not free that I was ever aware – it was a fixed-price app when I first got it – but you could store your vault on any network drive, and later Dropbox became the way to sync between mobile & desktop. But it was a bit tricky to set up with the extra auth & auth hassle and "now where did I put my vault?" issues. As much as I liked that approach, it's hard to deny the current cloud-based service is easier to get going with.