Bitcoin timestamp
Prove a file existed on a date ā and hasnāt been changed since. The record goes to Bitcoin, itās free, needs no sign-up, and your file never leaves your computer.
Stamp
The file isnāt 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.
Fingerprint
Your browser calculates the fileās sha256. Change one comma and the whole fingerprint changes.
Record on Bitcoin
The fingerprint goes to the OpenTimestamps calendars, which write it into a Bitcoin block within a few hours.
Your proof, forever
You keep the .ots file. Anyone can check it here or at opentimestamps.org ā without depending on Anyza.
What itās 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 werenāt edited afterwards.
Frequently asked questions
What exactly gets recorded?
Only the fileās 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 donāt keep the proof either: it stays with you.
Does this count as an official record?
Itās technical proof that the file existed on a date, increasingly accepted as evidence, but it doesnāt 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 āpendingā until the record enters a Bitcoin block ā usually 1 to 12 hours. After that, use āCheckā 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 OpenTimestampsā public calendars, which bundle thousands of records into a single Bitcoin transaction.
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Free tool based on OpenTimestamps. We donāt store files or proofs. The record proves a file existed on a date; it doesnāt prove authorship or replace official registrations.