Blockchain Document Notarization
Anchor proof of a document's existence into the Bitcoin blockchain — free, no signup, the file itself is never uploaded.
Choose a file — hashing happens in your browser, the file itself is never sent anywhere.
How it works: your browser computes the file's SHA-256 hash, and only that hash (not the file) is sent to the public calendar servers of the OpenTimestamps protocol, which anchor it into the Bitcoin blockchain. The resulting .ots file is a standard, open format you can independently verify at opentimestamps.org.
Full blockchain confirmation (inclusion in a block) usually takes a few hours. The .ots file you receive immediately records a preliminary timestamp; for full independent verification, use opentimestamps.org later. This does not substitute for a legal opinion on a document's evidentiary weight in a specific case.
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