A blockchain timestamp is an atypical proof. In most jurisdictions, it is admissible evidence and shifts the burden of contestation onto the opposing party — they must demonstrate the anchor was tampered with, which is computationally infeasible. It is not the same as a qualified electronic signature, but for proving existence and integrity of a document at a point in time, it is robust and court-tested.

No. We compute the SHA-256 hash entirely in your browser and transmit only the 64-character fingerprint. The hash is a one-way function — your original file cannot be reconstructed from it.

The merkle root is also anchored on Bitcoin via OpenTimestamps. As long as one of the two chains survives — which is essentially guaranteed for Bitcoin — your proof remains verifiable. The verification logic is open and documented.

Yes. Every stamp has a public /verify/[hash] page. Upload the original file, and the system recomputes the hash, fetches the merkle proof, and queries the on-chain root. Any third party — including a court expert — can reproduce this verification.

No, never. We store only the hash, metadata you provide (filename, size, mime type — optional), and the merkle proof. You keep your document.

A notary-issued timestamp in the EU typically runs €50–€200 per document. BA | Stamp starts at $2.99 with equivalent evidentiary weight in civil matters, and is instantly reproducible across all recipients.

Yes. The PDF certificate is self-contained and readable without any technical background — it shows the document fingerprint, the blockchain anchor, and a plain-language verification procedure. Any party, including the judge or a court-appointed expert, can independently re-verify the timestamp using the public /verify/{hash} page or the open-source verifier on GitHub — no account, no trust in BA | Stamp required.

You do. BA | Stamp never receives, sees, or stores the original file — only the 64-character SHA-256 fingerprint computed in your browser. Chain of custody of the original document remains entirely on your side. What the timestamp proves is that a file with that exact fingerprint existed at the on-chain block time and has not been altered since. Any later modification — even one byte — produces a different hash and breaks the link.

The PDF certificate already contains the full Merkle inclusion proof, the smart-contract address, and a numbered step-by-step verification procedure — usually sufficient as a self-contained annex. For complex or high-stakes cases, an independent expert can commission a formal perizia referencing the certificate plus the open-source stamp-verify tool; everything needed to reproduce the verification is public.