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).
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).
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.
Drop any document below. It's fingerprinted right here in your browser; nothing is uploaded.
Drop a file here — or browse
Your file never leaves this browser — we cannot read it, reconstruct it, or be compelled to disclose it
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.