Hashstamp

Name: Hashstamp
Author: ops zknot.io and William Shane Wilkinson

For developers: Hashstamp creates tamper-proof file receipts verified in-browser so recipients confirm authenticity without trusting servers.

Built by ops zknot.io and William Shane Wilkinson · Developer Tools · SaaS · Freemium

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ops zknot.io and William Shane Wilkinson (Joined Jul 2026)

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Launched on Launch Llama Jul 27, 2026 · #114 of 128 that day

About

HashStamp makes a receipt for a file.

Drop a file into the page. It is hashed in your browser with SHA-256 — the file never leaves your device, is never uploaded, and cannot be reconstructed from what we receive. We do not even get the filename. You get back a short code and a link.

Send that link to anyone. The check runs in their browser, against the record. They are not reading a green tick that our server decided to show them — they are computing the verdict on their own machine. No account, on either side.

What the record actually proves: that a file with that exact SHA-256 fingerprint was submitted to HashStamp at the stated time, that the fingerprint was signed by the HashStamp service key, and that the record is hash-linked into a tamper-evident chain, so any later change to the file breaks the match.

What it does not prove, stated plainly:

Not who created the file, or who sent it.
Not that a recipient received it.
Not an independently anchored time. The timestamp is HashStamp's own — we are not an external timestamp authority and we do not pretend to be one. It is tamper-evident, not tamper-proof.
Not identity. The signature is a hosted service key, not a secure element on a device.

Pair a stamp with your delivery record — an email, an upload log, a shared link — and together they show which version you delivered and when.

That last section is not a disclaimer we were made to write. It is the product. Everything ZKNOT builds produces a record a skeptic can verify, and every record states how strong it is. HashStamp is the free, software end of that ladder. The hardware end makes stronger claims on the same rail, and you check it exactly the same way.

Key Features

Delivers your file never leaves your device, SHA-256 is computed in your browser
Delivers we never receive the file, its contents, or even its filename
Delivers the verdict is computed in the checker's browser, not served by us
No account required, not to stamp, and not to verify
Surfaces fingerprint, timestamp and chain linkage can't be edited or deleted
Surfaces the timestamp is ours, not an external authority's, and the page says so

Use Cases

Stamp the deliverable before you send it, so "that's not what I got" is a link
Stamp a scope of work before signing, so scope creep has a dated baseline
Stamp a pitch deck or financial model the day you write it
Stamp a release manifest in CI so customers can verify what they downloaded
Stamp an invention note the day you write it — a dated record, not a filing

Who it is for

HashStamp is for people who may one day have to prove which file they had, and when — to someone with a reason to doubt them. It proves that a specific file existed at a stated time. It does not prove authorship, identity, or delivery, and the verification page says so.

Freelancers and agencies who need to prove which version they delivered
Consultants and contractors stamping a scope of work before the engagement
Designers and writers dating creative work before it leaves their hands
Engineers stamping release manifests so customers can verify the build they rece
Researchers and analysts dating a dataset or draft ahead of publication or audit

Pricing

One-time payment. No subscription. HashStamp is in founding pricing: it starts at $49 and steps up as founding seats fill, reaching $99 on 2027-01-26. [INCLUSION CLAUSE] The exact current price is shown and confirmed at Stripe checkout, which is authoritative.

View Hashstamp pricing →

Verdict

Use HashStamp if you want a dated, shareable receipt for a file that someone with no reason to trust you can check themselves — in about ten seconds, with no account and no upload on either side. The claim is deliberately narrow. A HashStamp record proves that a file with that exact SHA-256 fingerprint was submitted at a stated time, was signed, and is hash-linked into a tamper-evident chain, so any later change to the file breaks the match. It does not prove who made the file, that anyone received it, or that the time came from an independent authority — the timestamp is HashStamp's own, and that is on the product page rather than in a footnote. Don't use it if you need proof of authorship, proof of identity, a statutory notarization, or a timestamp issued by a neutral third party. If independent time anchoring is a hard requirement, OpenTimestamps is the better fit and we'll say so. What you're actually buying is a receipt you can hand to a skeptic, and a company that tells you where the receipt stops. HashStamp is the software rung of ZKNOT's verification ladder; the hardware rungs make stronger claims on the same rail, and you check every one of them the same way.