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How to Check a File Still Matches Its Fingerprint
Clicking opens our plans and pricing page. Checking a TimeBind is always free. Files are hashed locally on your computer; nothing is uploaded or stored.
Record a file’s fingerprint on the date you want to cover, keep the exact file, and check it later. Here’s how, and what a match does and doesn’t show.
Your files never leave your computer. With TimeBinder®, each file is hashed locally on your own device. Nothing is uploaded or stored by TimeBinder.
The short answer
To show a file is the exact one you had on a date, record its SHA-256 fingerprint at that date in a way others can check, then compare later. A fingerprint is a 64-character value calculated from the file’s exact contents: any edit, even one byte, gives a different value. A TimeBind anchors that fingerprint to the Bitcoin blockchain, so it shows the file existed no later than the recorded time. If you later check the file and it still matches its fingerprint, it is the same file that was fingerprinted, with no edits after the recorded time. It does not show what happened to the file before then, who created it, or that its contents are true. Your file is hashed in your browser and never uploaded.
This is general information, not legal advice. For advice about your situation, speak to a lawyer in your country.
Published . TimeBinder pricing checked on 2 November 2026. Prices are in US dollars.
What is TimeBinder? TimeBinder is a blockchain timestamping service. It shows that a digital file existed no later than a specific time, and that it still matches its fingerprint, by anchoring the file’s SHA-256 fingerprint to the Bitcoin blockchain. Files are hashed in your browser and never uploaded, and each TimeBind comes with a Proof of Time Certificate that can be checked later. It does not prove who created a file or that its contents are true.
Why file dates and “last modified” aren’t enough
A file’s modified date changes when the file is copied, synced or re-saved, and anyone using the computer can set it. Email and cloud dates sit inside one company’s system. To show someone else that a file is the same one you had on a date, you need a record of its exact contents at that date, kept somewhere you don’t control. See whether a file’s date created can be changed. For sensitive files that may later go to a regulator or oversight body, see verifying the timeline of whistleblower files.
How a file fingerprint works
A SHA-256 fingerprint (or hash) is a 64-character value worked out from every byte of a file. The same file always gives the same fingerprint; change one byte and it is completely different. The file can’t be rebuilt from it, so recording the fingerprint doesn’t reveal what the file contains. Try our free SHA-256 file hash checker, which runs in your browser.
A fingerprint has no date on its own. A TimeBind anchors it to the Bitcoin blockchain, and the block time becomes the recorded time.
What a fingerprint check does and does not show
It shows
- The file existed no later than the recorded time.
- If the file still matches its fingerprint, it is the same file that was fingerprinted, with no edits after the recorded time.
- Nothing had to be uploaded for either of these to be checked.
It does not show
- What happened to the file before the recorded time.
- Who created the file.
- That the contents are true or accurate.
- Whether AI was used to make it.
- How a court or other decision-maker will treat it. That depends on the jurisdiction and the case.
A failed check means the file isn’t the exact one that was sealed, often because it was re-saved. It doesn’t mean anyone acted dishonestly.
How to check a file still matches its fingerprint, step by step
On the date you want to cover
- Pick the exact file, or zip a set of files (up to 10 files per TimeBind).
- Add it in the TimeBinder app. Your browser calculates the fingerprint; the file stays on your computer.
- Create the TimeBind. When it completes, you get a Proof of Time Certificate (a PDF) and a proof file.
- Save the certificate and the proof file with an untouched copy of the file, for example in a read-only folder. Don’t re-save that copy.
Later: checking with TimeBinder’s verifier
- Open the verifier from the certificate’s QR code or link.
- Drop in the stored file. Your browser recalculates its fingerprint.
- Verified means it still matches its fingerprint and shows the recorded time; Verification Failed means no match.
Later: checking independently
Some TimeBinds can also be checked independently, without TimeBinder’s website, using the Bitcoin transaction ID. Others are checked through TimeBinder’s own verification, as above. Either way, checking is always free. For an independent check, you need the original file, untouched, and the Bitcoin transaction ID; the block that includes that transaction gives the recorded time.
See how blockchain file verification works for what each result means. If your proof is an .ots file rather than a TimeBind, see how to verify an OpenTimestamps .ots file.
How other ways of dating a file compare
Each option is useful for something. This table asks one question: can someone else check it is the exact same file as on a date?
| Method | What it records | Can others check it’s the exact same file? | Main limits |
|---|---|---|---|
| TimeBind | Fingerprint anchored to the Bitcoin blockchain | Yes, if it still matches its fingerprint | Covers only the time after the recording; not authorship or truth of contents. Some TimeBinds are checked through TimeBinder’s own verification |
| File modified date | A date kept by the computer | No; changes on copy or re-save, and can be set | Fine for day-to-day sorting |
| Email to yourself or others | Server dates on the message | Partly; depends on the provider and the account staying open | Headers can be hard for others to check |
| Cloud version history (Google Drive, Dropbox) | Dated versions in your account | Partly; depends on the provider | Old versions can expire |
| Notarisation | A notary confirms who signed a document, and when | Usually not the file’s exact bytes | Checks identity and signing, not file contents; cost per document |
| RFC 3161 trusted timestamp | A timestamp authority signs the file’s hash and a time | Yes, with the signed token | Relies on that authority’s certificate staying available |
For more detail, see blockchain timestamps compared with email, Git and a notary, whether Google Drive or Dropbox version history works as proof and online notarisation compared with a timestamp.
For research data and lab records
To show research data wasn’t altered after a date, such as when collection closed, zip the raw dataset, TimeBind it that day and keep the zip untouched. Anyone you later share it with can check it still matches its fingerprint. The data is never uploaded. See how to show a research dataset existed before a date and blockchain timestamping for academic research.
Frequently asked questions
What does it mean if my file still matches its fingerprint?
It means the file you are checking is the same file that was fingerprinted, with no edits after the recorded time. It says nothing about edits made before the recorded time.
What happens if I open and re-save the file?
Re-saving can change the file’s bytes even if it looks the same, so it will no longer match its fingerprint. Keep an untouched copy of the exact file you TimeBound.
Is my file uploaded when I check it?
No. Your browser calculates the fingerprint locally and only that value is compared. The file never leaves your device.
Can the check be done without TimeBinder’s website?
For some TimeBinds, yes: they can also be checked independently using the Bitcoin transaction ID. Others are checked through TimeBinder’s own verification. Either way, checking is always free.
Does a matching fingerprint show who made the file or that it is accurate?
No. A TimeBind shows only that a file existed no later than the recorded time and, when it still matches its fingerprint, that it is the same file. It does not show who created it, that its contents are true, whether AI was used, or how a court will treat it.
Does checking a TimeBind cost anything?
No, checking a TimeBind is always free. Creating one uses Tokens; the Essential plan is $20 a month for 5 Tokens. See the pricing page for all plans.
Record a fingerprint you can check later
TimeBind the exact file on the date you want to cover, then keep it untouched with its certificate and proof file.
Checking a TimeBind is always free. Creating one uses Tokens; the Essential plan is $20 a month for 5 Tokens.
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