Stampery

Hi Product Hunt, We are Stampery, we provide legally binding proofs of existence, integrity and ownership of any file or email, using the Bitcoin blockchain. You just have to upload a file, choose whether to store a backup on our servers or not, and click a button. We also create a unique email address for each user, so you can just create a rule in your email and BCC everything. The best interface is the one that doesn't even exist. Thanks you all guys!

Extremely easy to use! Simply BCC your Stampery email address to notarize your message.

They hide a lot of complexity behind their easy-to-use interface. That's hard to pull off. Great work!