This website requires JavaScript. The certification service calculates the cryptographic digest of your document client-side. Alternatively, you can calculate and submit your document data using shasum and curl. See the Developer API for more information, read our about page, get the news, or contact us.

The original Blockchain notary service

Instant & secure Proof of Existence for any document

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Select a document and have it certified in the Bitcoin blockchain

Drag and drop your document here, or choose a file. The file will not be uploaded. Learn more.

Input a Document Hash

Compute the SHA256 checksum hexadecimal digest for your file, and input the value here.


Documents registered for certification


Documents confirmed in the blockchain