KeepsakeDocument Notary
A signed contract, a will, a piece of evidence: sometimes the question is not "is it safe?" but "can you prove it existed on that date, exactly like this?" Keepsake answers with mathematics instead of a notary's stamp.
The problem
Proving a document's age and integrity traditionally means notaries, fees and appointments — so almost nothing gets notarised until a dispute makes it too late. Digital timestamps from commercial services are only as durable as the company issuing them.
How Keepsake solves it
⚓Anchor with one tap
Keepsake computes the document's SHA-256 fingerprint and anchors it via OpenTimestamps into the Bitcoin blockchain — the fingerprint, never the document.
📜A receipt anyone can check
You get a small receipt file. Anyone can verify it against the document — on our /verify page or with any OpenTimestamps tool — no Keepsake required.
🕰️Proof that outlives us
The anchor lives in Bitcoin's public ledger. It stays verifiable even if Keepsake, and every notary service, disappears.
Under the hood — OpenTimestamps
- Only the 32-byte SHA-256 hash leaves your device — the document itself never does, and a hash is not reversible into content.
- OpenTimestamps aggregates hashes into a Merkle tree and commits the root to a Bitcoin transaction; your receipt is the Merkle path from your hash to that transaction.
- Verification recomputes the document hash locally and checks the path against the public blockchain — trustless, free, offline-capable once headers are cached.
- The /verify page runs this entirely in client-side JavaScript; drop the file and the receipt, get a yes/no and the anchored date.
Trust through specificity: the full crypto design is documented on the security page.
Questions
Do I need a crypto wallet or account?
No. Anchoring uses the free public OpenTimestamps calendars, and verification only reads public block data. There is no wallet, no fee and no account anywhere in the flow.
Does this put my document on a blockchain?
No — only a cryptographic fingerprint (SHA-256 hash) is anchored, and it is blinded with a random nonce before submission. The document never leaves your vault, and nothing about its content can be recovered from the hash.
Is anchoring free?
Anchoring is a Premium feature. Verification is free for everyone, forever — including the public /verify page, which anyone can use with any Keepsake .ots receipt.