KnownSince

Prove it existed.
As of today.

Timestamp anything — an idea, a draft, a photo, a contract — and get a certificate that proves it existed on this date. Anyone can check it. No one can fake it.

Your content's fingerprint

Start typing or pick a file to see its fingerprint

Only the fingerprint is sent to us — never your content. The fingerprint can't be reversed to reveal what you wrote.

How it works

1

Fingerprinted on your device

Your content is turned into a unique 64-character fingerprint, right here in your browser. Change a single letter and the fingerprint changes completely.

2

Written into Bitcoin

The fingerprint is anchored into the Bitcoin blockchain — a public record that no person or company can rewrite. Not even us.

3

Provable forever

You get a certificate and a receipt file. Anyone can verify them independently — even if this website no longer exists.

Read the full explanation →

People use this for

Common questions

Is my file uploaded somewhere?

No. Your text or file is fingerprinted inside your browser and never sent to us or anyone else. We only ever see the fingerprint — 64 characters that reveal nothing about your content.

What does a timestamp actually prove?

That your exact content existed no later than a certain date and time. It's strong evidence for "I had this first" — though it isn't a patent or copyright registration.

Why should I trust you?

You don't have to — that's the point. Proofs are built on the open OpenTimestamps standard and anchored in Bitcoin. Anyone can verify them with free, independent tools, even if this site disappears.

Do I need to know anything about Bitcoin?

No. We only use Bitcoin as a public, tamper-proof clock. You never need a wallet, an account, or any cryptocurrency.

What does it cost?

Stamping is free. Your proof usually becomes fully anchored within a few hours, and your certificate page updates automatically.