What is proof of existence for a file?

What does a proof of existence actually prove?

A proof of existence shows that one specific file already existed at a certain moment in time. It works by creating a unique fingerprint of the file. If even a single character changes later, the fingerprint becomes completely different.

So the proof is tied to the exact contents of the file — not just its name or its folder. It’s concrete evidence, not a vague claim.

Why your file stays private

The clever part is that only the fingerprint is needed, not the file itself. Think of it like a wax seal on a letter: it proves the letter wasn’t opened, without anyone needing to read what’s inside.

That means you can create the proof entirely on your own computer. Only the fingerprint is saved to a permanent record online, while your document stays with you.

• Your original file is never uploaded or shared.
• Anyone with the same file can check the proof later.
• It proves the contents haven’t changed, not just that a filename exists.

When is it useful?

Proof of existence is most valuable when timing matters: contracts, creative work, research notes, business records, photos, or anything you might need to show existed before a certain date.

It’s best created before a problem comes up — not after. Think of it as insurance for your documents.