The founding idea, what Satohash is today, the honest gaps, the next chapter, and exactly who this is for — in plain language, no overclaiming. Start here if you want the whole thing.
Every dispute over “who did what, when” eventually comes down to one question: can you prove your version of events without asking anyone to take your word for it?
For centuries the answer was a notary, a lawyer, a registry, a company — some trusted third party who could vouch for a date. Satohash's founding bet is that this middleman is no longer necessary. OpenTimestamps anchors a fingerprint of your file into the Bitcoin blockchain, permanently and verifiable, with no company standing between your document and the proof. Add a private-key signature, and “this file existed” becomes “this file existed, and I am the one who created it” — proof of existence upgraded to proof of authorship, with nobody's permission required.
That's the whole idea. Everything below is either an explanation of it or a plan for growing it.
Satohash is a free, no-account browser tool. You drop in a document, contract, photo, or dataset, and it's hashed locally in your browser. Only the hash — a SHA-256 fingerprint — is sent out to be anchored into Bitcoin's next block via OpenTimestamps.
Once it's in a block, that timestamp can't be altered, backdated, or quietly removed — not by Satohash, not by anyone. Verification doesn't depend on Satohash staying online: proofs can be independently checked years later through opentimestamps.org, community CLI tools, or by inspecting the Bitcoin blockchain directly.
It's the most decentralized, longest-running, most attacked-and-survived public ledger that exists. Tens of thousands of independently operated nodes worldwide validate it, with no single company that could be bought, breached, or shut down. That's not marketing — it's the actual property that makes the proof durable.
Proving a document, photo, manuscript, or dataset existed by a certain date — priority disputes, “I had this first,” audit trails, discovery dates for research and IP. Frameworks like the US ESIGN Act and UETA, and the EU's eIDAS regulation, recognize timestamped electronic records as admissible evidence; Satohash produces exactly that kind of record.
Read this plainly: admissibility isn't the same as automatic proof of a specific legal conclusion — a court still weighs evidence in context. Satohash gives you strong, independently verifiable evidence of a date; it isn't a substitute for legal advice about your specific situation. Admissible, not presumed accurate.
Free — and that free base is the permanent trust anchor, never paywalled. The reconciled, Cam-locked model: free base (unlimited stamp / verify / .ots + client-side hashing, 10 stamps/day cap) + optional premium tiers (Professional ~2,100 sats/mo, Business ~21,000 sats/mo) + a pay-per-use API (1–5 sats/stamp via L402). The anchoring mechanism and its guarantees are identical across every tier.
A mission document that only lists strengths isn't trustworthy. Here's the honest gap list, because closing it is the roadmap:
| Limit | What it means in practice |
|---|---|
| Proves “when,” not “who” | Anyone can stamp any file. Possession of a hash isn't proof of authorship — yet. |
| One-way | No signing, no encryption, no access control. Satohash timestamps; it doesn't protect or redact. |
| No identity layer | Nothing currently ties a proof to a specific person's cryptographic key. |
| Hash confidentiality has edges | The file itself never leaves your device — but a hash of a short, guessable, or low-entropy input (e.g., a single common word) can theoretically be reverse-matched via lookup tables. Fine for real documents; not a privacy shield for trivial inputs. |
| ~60-minute confirmation | Anchoring waits for the next Bitcoin block. Not instant — by design, since block time is what makes the proof strong. |
| Bitcoin-only | Satohash is a Bitcoin-only company. No multi-chain anchoring, ever. |
The single sentence that matters most: Satohash today proves existence. Adding a private-key layer turns that into proof of authorship — and that upgrade is the whole next chapter.
Bitcoin is the most battle-tested public ledger in existence. OpenTimestamps is the open protocol that writes facts to it. Private-key cryptography is the missing piece that turns an anonymous fact into an authored one. Put together, they form a record that is trustless, sovereign, and quiet by design: your document never leaves your device, only a fingerprint ever touches the chain, and the resulting proof outlives Satohash itself, any single company, and any single government.
Scope: grow Satohash from a tool that proves existence into a layer that proves authorship and origin — a free base (never paywalled) plus optional premium tiers (Professional ~2,100 sats, Business ~21,000 sats) plus a pay-per-use API, available to anyone, in any industry, with no notary and no permission required. The legal standards already exist (ESIGN, UETA, eIDAS). The chain already exists. The work left is making this feel as simple, obvious, and trustworthy as reaching for a pen.
Status: mission & scope, v3 — written by Cam's article + Gemini use cases, given a Claude pass, and published by the Give A Bit family. Scope is meant to be rebalanced with the group; cut what doesn't earn its place; lock concrete near-term goals. Free non-commercial today, Bitcoin-only, no invented entity.