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Bitcoin timestamp · free

Bitcoin timestamp: prove your file existed

Prove a file existed on a date — and hasn’t been changed since. The record goes to Bitcoin, it’s free, needs no sign-up, and your file never leaves your computer.

  • Free
  • No sign-up
  • Your file never leaves your computer
  • Recorded on Bitcoin
  • Anyone can check

Stamp

The file isn’t uploaded: your browser calculates the fingerprint (sha256) and only that goes into the record.

Check a record

Choose the original file and the proof (.ots). We check the math up to the Bitcoin block and, if the proof is still waiting, try to complete it.

How it works

1

Fingerprint

Your browser calculates the file’s sha256. Change one comma and the whole fingerprint changes.

2

Record on Bitcoin

The fingerprint goes to the OpenTimestamps calendars, which write it into a Bitcoin block within a few hours.

3

Your proof, forever

You keep the .ots file. Anyone can check it here or at opentimestamps.org — without depending on Anyza.

Why record on Bitcoin?

Bitcoin is the most secure public record there is: every block is stored on thousands of computers around the world and can’t be erased or turned back in time. Once your file’s fingerprint enters a block, it’s proven that it already existed at that moment.

You don’t have to trust Anyza: the proof (.ots) is an open standard, OpenTimestamps, and can be checked in any client or at opentimestamps.org — even if Anyza ceases to exist.

What it’s for

  • Contracts and agreements

    Show which version of the document existed on the day it was signed or sent.

  • Art, photos and music

    Register the work before publishing and have technical proof of prior existence if someone copies it.

  • Code and projects

    Stamp a project zip or a commit and prove what was already done on a date.

  • Ideas and texts

    A script, a manuscript, a prediction: register the text now and show later that you got there first.

  • Evidence and screenshots

    Screenshots, audio and video of a conversation or a problem: prove they weren’t edited afterwards.

Frequently asked questions

What exactly gets recorded?

Only the file’s fingerprint (sha256 hash). It proves that exact file existed at the time of the record, but reveals nothing about the content.

Do you receive or keep my file?

No. The calculation is done in your browser and the file is never uploaded. We don’t keep the proof either: it stays with you.

Does this count as an official record?

It’s technical proof that the file existed on a date, increasingly accepted as evidence, but it doesn’t replace a notary, trademark or copyright registration when the law requires one. If in doubt, consult a lawyer.

How long does it take?

The proof is issued right away, but stays “pending” until the record enters a Bitcoin block — usually 1 to 12 hours. After that, use “Check” to see the date and download the complete proof.

What if I lose the file or the proof?

You need both: the original file, with no changes at all, and the .ots. Keep them together, preferably with a backup.

How much does it cost?

Nothing. The record uses OpenTimestamps’ public calendars, which bundle thousands of records into a single Bitcoin transaction.

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