The certification service calculates the cryptographic digest of your document client-side.
Alternatively, you can calculate and submit your document data using
See the Developer API for more information, read our about page,
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The original Blockchain notary service
Instant & secure Proof of Existence for any document
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