Free, offline, no account
Fingerprint your files without sending them
Choose the files you want sealed. This page works out each file's SHA-256 fingerprint inside your own browser, so the files never leave your computer. You send us only the fingerprints. We never see the files.
This page's fingerprint engine failed its own check, so it has stopped. Do not use it. Use the commands below instead, and tell us at ibg@bestfortifiedpay.com.
Drop files here, or choose them
Large files are fine. They are read in pieces and nothing is uploaded. The page makes no network requests (its content policy forbids them), and you can save it and use it offline.
| Item | File | Size | SHA-256 fingerprint |
|---|
What to send us
This box shows exactly what you would send. Nothing else about your files is in it.
If you chose item numbers, keep the private copy. It is the only place that links each number to its file name. We never receive it.
Things worth knowing
- A fingerprint is not the file. It is a 64-character value worked out from every byte of the file. It cannot be turned back into the file, and it reveals nothing about what is inside.
- It does change if anything changes. Change one byte, even a date inside a photo, and the fingerprint is completely different. That is what makes it useful later.
- The same file always gives the same fingerprint. Someone who already has an identical file could confirm it matches. File names can reveal more than fingerprints do, which is why you can replace them with item numbers.
- Keep your originals exactly as they are. Do not edit, rename-and-resave, or re-export them. To check a file against a receipt later, you fingerprint it again and compare.
- The time in the list is your computer's clock. It is not an independent time. An independent timestamp is added when we seal.
- Do not send passwords, financial account numbers or government ID numbers in any form, including in file names.
Prefer a command? These give the same answer
Each one prints the SHA-256 of a file. Use whichever your computer has.
Mac or Linux: shasum -a 256 "my file.pdf" Windows: Get-FileHash "my file.pdf" -Algorithm SHA256
If a command and this page ever disagree for the same file, tell us right away.