- opentimestamps.org simply uploads its payload to an op return transaction - the python client looks nice; it can connect to either a local node or a remote server - it has a bunch of political boilerplate around hashing content. this boilerplate could be removed and it could be used a simple op_return client to notarise small data for public lookup the file hashing boilerplate entrypoint is in opentimestamps-client/otsclient/cmds.py lines 155-182 (off 616718cfdc5c235ea71374d6910235d77ec47fc0 ). It loops over each file, hashes, adds a nonce, and merkles the hashes. The resulting merkle tip could be replaced with any short content (likely of identical length) to notarise this content. I am not a cryptographer. I might propose either the first n/2 bytes of 2 different modern hashes preceded 1-4 bytes of topic-specific identifier, a common hash such as sha256, or something that can be searched for elsewhere, such as a cleartext commit hash, an infohash, or a url in a content-indexed network. Scrubbing the blockchain for similar strings could help find existing uses to join a larger community.