Proof of Existence is a website and web application that allows users to securely store a cryptographically-verified record of any digital document or file. It is an application that uses the blockchain technology to timestamp and verify the existence of any document. The website allows users to upload a document, which is then timestamped and added to the blockchain. This creates an immutable record of the file's existence, making it difficult for anyone to refute the document's existence. The website also allows users to search the blockchain for any documents related to a particular topic. This makes it possible to quickly verify the authenticity of a document, eliminating the need for costly and time-consuming authentication processes.
ZeroID
Stampery
OriginStamp.com
Woleet
Same functionality, but free and with a good API integration.