Proof of Original
Free File Timestamp & SHA-256 Certificate

Free Proof of Original: Prove Your File Existed Before a Date

When your work is copied, reposted or claimed by someone else, the first question is simple: who had it first? A file's "date modified" can be changed in seconds, and a screenshot of a folder proves nothing. A cryptographic timestamp solves this. It gives you neutral, third-party evidence that a file with exactly this content existed on or before a specific date, without trusting any company, including this website.

What is a SHA-256 hash (file fingerprint)?

A SHA-256 hash is a 64-character code calculated from the exact bytes of a file. The same file always produces the same hash, while changing a single pixel, letter or frame produces a completely different one. The hash cannot be reversed, so sharing it reveals nothing about the content. That is why this tool only sends the hash for timestamping, and your video, design or document stays on your device.

How does OpenTimestamps and Bitcoin make the date trustworthy?

OpenTimestamps is a free, open standard. Public calendar servers collect many hashes, combine them into a single value and commit that value into a Bitcoin transaction. Once that transaction is in a Bitcoin block, nobody can alter the date, because changing it would mean rewriting the Bitcoin blockchain. Your .ots file contains the path that links your hash to that block, so anyone can verify it independently, even if this website no longer exists.

Pending vs confirmed proof

Immediately after you click Create Proof, the proof is pending: your hash has been accepted by the calendar servers but is not in a Bitcoin block yet. This usually takes a few hours. Keep the .ots file and, later, upload it with your original file on opentimestamps.org to upgrade it into a fully confirmed proof that shows the exact block date. Save the upgraded file in place of the old one.

What this proof does and does not show

• It shows that a file with exactly this content existed on or before the confirmed date.
• It does not show who created the file. Combine it with drafts, project files, raw footage, emails and exports to build a stronger case.
• It is not a formal copyright registration or legal advice. Courts and platforms may treat it as supporting technical evidence, depending on your country.
• It only matches the exact file. Compressing, re-exporting or editing the file creates a new fingerprint, so keep the untouched original.

Best practices for creators

• Timestamp your raw project and final export before you publish or send drafts to anyone.
• Store the original file, the .ots proof and the certificate together in at least two places (Drive and a pendrive).
• Do not rename-and-resave the original. Copy it if you need to work on it, and keep the first file intact.
• Use the Verify Proof tab once after downloading to confirm that the file and the proof match.
• After a few hours, upgrade the proof on opentimestamps.org and replace the pending .ots with the confirmed one.
• For high-value work, also keep dated drafts, project files and communication, which show how the work was created.

Why a certificate image and JSON record?

The certificate PNG is a readable summary for portfolios, clients and disputes: file name, size, SHA-256 hash, a certificate ID and the timestamp status. The JSON record is the same data in machine-readable form for your archive. Neither replaces the .ots file: the trusted date comes only from the Bitcoin-anchored proof, not from the image or from your device clock.

Preparing files first? Reduce image size with our Image Compressor before you timestamp the final version, or protect your published images with the Watermark Tool. Remember to timestamp the exact file you plan to keep as the original.