Prove the existence and integrity of any document at a precise moment in time. Cryptographic hashes anchored on Polygon and Bitcoin. Admissible under eIDAS 2.0, Art. 2712 of the Italian Civil Code, and US FRE 901(b)(9).
Drop a file here — or browse
Your file never leaves this browser — we cannot read it, reconstruct it, or be compelled to disclose it
Prove the existence and integrity of any document at a precise moment in time. Cryptographic hashes anchored on Polygon and Bitcoin. Admissible under eIDAS 2.0, Art. 2712 of the Italian Civil Code, and US FRE 901(b)(9).
Drop a file here — or browse
Your file never leaves this browser — we cannot read it, reconstruct it, or be compelled to disclose it
Your file never leaves your browser. We compute SHA-256 client-side and transmit only the 64-character fingerprint.
Hashes are aggregated into a merkle tree. Each user gets a cryptographic proof binding their hash to the batch root.
The merkle root is written to a smart contract on Polygon (primary) and submitted to Bitcoin via OpenTimestamps (secondary).
Anyone can verify independently: recompute the hash, supply the proof, query timestamps(root) on-chain. No intermediary.
Blockchain timestamps are recognized as atypical proof in most legal systems. The burden of contestation falls on the opposing party.
| Jurisdiction | Reference |
|---|---|
| Australia | Electronic Transactions Act 1999; Evidence Act 1995 s. 146–147 |
| Austria | SVG BGBl. I Nr. 50/2016; § 292 & § 294 ZPO; eIDAS |
| Belgium | Code civil Art. 8.1–8.28; Digital Act 2016; eIDAS |
| Brazil | Lei 14.063/2020; MP 2.200-2/2001; CPC Art. 411 |
| Canada | Canada Evidence Act s. 31.1–31.8; provincial ECAs |
| China (PRC) | Electronic Signature Law (2004, rev. 2019); CPL Art. 63 |
| Czech Republic | Zákon č. 297/2016 Sb.; OSŘ § 125; eIDAS |
| Denmark | Lov (2016) om eIDAS; Retsplejeloven § 344 |
| European Union | eIDAS 2.0 Art. 41 — Regulation (EU) 2024/1183 |
| Finland | Laki sähköisistä allekirjoituksista; OK 17:17 §; eIDAS |
| France | Code civil Art. 1365–1367; eIDAS |
| Germany | § 371a ZPO; eIDAS |
| Hungary | 2015. évi CCXXII. törvény; Pp. 325 §; eIDAS |
| India | IT Act 2000 s. 3-3A; Evidence Act s. 65B |
| Ireland | Electronic Commerce Act 2000 s. 12–13; eIDAS |
| Israel | Electronic Signature Law 5761-2001; Evidence Ordinance s. 41A |
| Italy | Art. 2712 c.c.; D.Lgs. 82/2005 CAD Art. 20 & 41 |
| Japan | Act on Electronic Signatures (Law 102/2000) |
| Mexico | Código de Comercio Art. 89 bis–95; LFEA |
| Netherlands | Art. 156a Rv; Wet elektronisch bestuurlijk verkeer; eIDAS |
| Norway (EEA) | Lov om elektroniske tillitstjenester (2018); tvml. § 26-1 |
| Poland | Art. 308 KPC; Ustawa o usługach zaufania (2016); eIDAS |
| Portugal | DL 12/2021; CPC Art. 410; eIDAS |
| Romania | Legea 455/2001; CPC Art. 282; eIDAS |
| Singapore | Electronic Transactions Act 2010; Evidence Act s. 35 |
| Slovakia | Zákon č. 272/2016 Z. z.; OSP § 125; eIDAS |
| South Africa | ECT Act 25/2002 s. 11 & 15 |
| South Korea | Framework Act on Electronic Documents (2005) |
| Spain | Ley 6/2020; LEC Art. 299 & 326; eIDAS |
| Sweden | Lag (2016:561) om eIDAS; RB 35 kap. 4 § |
| Switzerland | ZertES; OR Art. 14 Abs. 2bis |
| Turkey | Elektronik İmza Kanunu No. 5070; HMK Art. 205 |
| UAE | Federal Decree-Law 46/2021 |
| United Kingdom | UK eIDAS (retained EU law); ECA 2000 s. 7; CPR Part 31 |
| United States | FRE 901(b)(9); FRE 902(14); ESIGN Act |
BA | Stamp is not a qualified trust service provider (QTSP) under eIDAS. We issue non-qualified electronic timestamps per Art. 41, which are explicitly recognized and admissible as evidence across the jurisdictions above. Qualified timestamps under Art. 42 — required in specific contexts such as certain long-term archival regimes — must be obtained from an accredited QTSP.
Including Chinese, Japanese, Arabic, and Hebrew. Every non-English certificate is issued bilingually (local language + English) so it travels across borders without requiring a translator.
File contents never leave your browser. Only the 64-character SHA-256 fingerprint is transmitted — we cannot read your document, reconstruct its contents, or be compelled to disclose it. We simply never receive it.
Polygon for fast finality and cost, Bitcoin via OpenTimestamps for long-term gravitas. Two independent attestations.
Public /verify pages let any third party confirm the anchor directly against the smart contract, with no account required.
Every stamp generates a jurisdiction-aware certificate with citations, merkle proof, and tx hashes.
The whole point is trustless proof. So the verifier itself is public, MIT-licensed, and reproducible from source. Anyone can re-verify a certificate independently — no account, no API key, no dependency on bastamp.com.
npm install -g stamp-verifyPrices in your local currency. Every plan includes the same blockchain anchoring, PDF certificate and public verification.
Your first stamp is free after sign-up. Explore the product before you buy.
All plans include: blockchain anchoring (Polygon + Bitcoin) · tamper-proof PDF certificate · public verification page · 30+ jurisdictions.
Secure checkout via Stripe
Legal framing for 30+ jurisdictions included.
Purpose-built for legal-grade timestamping.
| Capability | BA | Stamp | DIY / open-source | Typical timestamp service |
|---|---|---|---|
| Legal-grade PDF certificate | ✓ 30+ jurisdictions | ✗ | Partial |
| Dual-chain anchor | ✓ Polygon + Bitcoin | Bitcoin only | Single chain |
| Client-side hashing | ✓ Mandatory | ✓ | Optional |
| Trustless on-chain verification | ✓ Public smart contract | Requires archive node | Hosted verify only |
| No technical setup | ✓ Drop file and go | CLI / developer tools | Varies |
| Open-source verifier | ✓ Released | ✓ | ✗ |
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.
Cryptographic certificate ready before you finish your coffee.