In a browser
Open pasqio.com/verify. Drop in the original document and the certificate PDF. The page computes the document’s SHA-256 on your computer (the document is not uploaded), reads the proof attached to the certificate, and fetches the Bitcoin block header from blockstream.info and mempool.space. It reports whether the document matches, whether the proof reaches the block, and when the block was mined, plus the independent RFC 3161 signed time where the certificate has one.
§At opentimestamps.org
Open the certificate in a PDF reader and save the attached .ots file (Adobe Acrobat: View → Show/Hide → Navigation Panes → Attachments). At opentimestamps.org, drop the .ots file and the original document into the “Stamp & Verify” box.
§On the command line
Compare the document’s SHA-256 with page 1 of the certificate: shasum -a 256 document (Windows: certutil -hashfile document SHA256).
Check the Bitcoin proof with the reference client (pip install opentimestamps-client): ots info proof.ots prints the block and merkle root the proof reaches; ots verify -f document proof.ots checks it against a Bitcoin node.
Check the RFC 3161 token (the attached .tsr): openssl ts -verify -in token.tsr -data document -CAfile roots.pem.
§The seal
The certificate PDF is digitally sealed by Pasqio. Adobe Acrobat’s signature panel shows whether anything in the PDF has changed since it was issued. Pasqio’s sealing certificate is its own; a reader may show it as valid but not from a pre-trusted authority.
§Batches
A manifest certificate lists many documents certified together. Drop the manifest PDF and any one listed document into pasqio.com/verify: the page finds the document in the manifest and follows its path to the anchored root. Each document’s own certificate also carries a complete standalone proof.