There's also https://opentimestamps.org/ for timestamping into the bitcoin blockchain using a 'calendar aggregation' concept. Clients get back a merkle tree of hashes that can be used to show inclusion in a published hash on the blockchain.
I've been using opentimestamps/ots for a few years now. It can be used to show a specific version of a file existed as early as the proof date. Unfortunately the only other value seems to be showing that if you had doctored a file then that happened at least as early as the timestamp and not later.
I've been using opentimestamps/ots for a few years now. It can be used to show a specific version of a file existed as early as the proof date. Unfortunately the only other value seems to be showing that if you had doctored a file then that happened at least as early as the timestamp and not later.