Proof of existence VS OriginStamp

Write down everything you remember while it is still fresh, including all BTC addresses. You can even store a hash of your notes in the blockchain as proof of existence. Source: about 1 year ago

If that's not enough, you could publish a hash. Proof of Existence is a service that adds it to the blockchain so you can always prove it, but realistically that's overkill and I'm sure sticking it on Google Drive would be enough. Source: over 1 year ago

Bitcoin has proofofexistence.com. It hashes a file via the browser and stores the result in OP_RETURN. The current fee is around $7, which is no longer practical. Source: almost 2 years ago

Proof Of Existence is a service for this. You take the hash of the photo, then when you're picking random numbers to mine bitcoin, pick numbers that start with that. Once you've successfully mined a block, that number will be stored in the blockchain. Source: over 2 years ago

I am actually working on the whitepaper right now. Which I will be submitting my patent idea very shortly. To secure my idea on https://originstamp.com. Source: about 2 years ago

P.S. You should use OriginStamp or something similar to put the hash of the cafe transaction ID (a hash of a hash, I suppose) on a blockchain and tell us about it so that you can later prove that you did have a specific target transaction in mind. Otherwise, you could unfairly "change your mind" about the target transaction later. Source: over 2 years ago

2) To prove that your video or photo were collected no later than a certain date, you can hash the file and then post it to a blockchain, such as BTC or BCH. This service does that for you. I or others could help you do the technical parts. It shouldn't be too hard. Source: over 2 years ago