Proof that something existed, on a date
One call turns a hash into a signed, dated statement at a public address. Your file never leaves your side, because a signature over a hash is a signature over the bytes.
How it works
You hash it
SHA-256 on your side, in whatever language you already use. We never see the document.
We sign it
A dated statement, signed with a key only this deployment holds, and stored, so a dispute has an authority to point at.
Anyone checks it
A public page, a published key and the canonical bytes, so a buyer or a court can repeat the check without us.
One call
# 1. Hash it where the file already is. We never see it.
sha256sum msa-2026.pdf
# e3b0c44298fc1c14 9afbf4c8996fb924 27ae41e4649b934c a495991b7852b855
# 2. Ask for a receipt over that hash.
curl -X POST https://oakmonttechnologies.com/api/v1/notary/receipt \
-H "Authorization: Bearer oak_live_xxx" \
-H "Content-Type: application/json" \
-d '{"sha256": "e3b0c442...b855",
"filename": "msa-2026.pdf",
"reference": "CTR-4417"}'
# 3. What comes back is an address anybody can open.
# {"id": "9f3c...", "verify_url": "https://oakmonttechnologies.com/verify/9f3c...",
# "issued_at": "2026-08-24T09:00:00+00:00", "receipt": { ... }}What a receipt does not say
It proves the bytes and the date. It says nothing about whether the document is true, whether it binds anyone, or who wrote it. That sentence sits inside the signature, where nobody quoting it selectively can drop it.
What people put it on
- Contracts and statements of work, at the moment both sides agreed the wording.
- Model outputs, so an answer can be shown to be the one that was produced.
- Audit evidence and readings, where the date is the whole value.
- Backups and exports, to prove an archive has not been edited since.
Priced per receipt
A receipt is what your customer keeps, so it is the unit on the invoice. Every plan includes public verification, the published key and the daily Merkle root.