Fingerprint & verify a file
Get four separate hashes — bytes, text, visual and metadata — so you can prove the content stayed identical while the metadata changed, and check later whether a document was altered.
How it works
- 1. Upload a PDF, Office file, image or e-mail.
- 2. We compute the file hash, a metadata-free content hash and a metadata hash.
- 3. Save the fingerprint token; compare it later to prove the content is unchanged.
Fingerprint your file
PDF, Office, image or e-mail — separate hashes for content and metadata.
or drag and drop your files here
Without a proper fingerprint
- A raw 64-character SHA-256 string is impossible for a non-technical reader to interpret or cite.
- Two identical-looking PDFs get different byte hashes after a harmless re-save, which looks like tampering.
- Command-line hashing (certutil, shasum, Get-FileHash) isn't realistic for a lawyer, notary or client.
- A bare hash gives you no document you can actually file as evidence.
With PDFengine fingerprint
- Four separate hashes — file, text, visual and metadata — so you see what changed, not just that something did.
- Prove the content stayed identical even when the metadata was stripped or the file was re-saved.
- Save a fingerprint token and re-check any time to show a document is unchanged.
- Download an evidence PDF; works on PDF, Office, images and e-mail (per attachment).
How it works
Upload your file
Upload a PDF, Office file, image or e-mail.
Get four separate hashes
We compute the file hash, a metadata-free content hash and a metadata hash.
Save & re-check later
Save the fingerprint token; compare it later to prove the content is unchanged.
When to fingerprint a file
Prove integrity for legal, compliance and everyday document checks.
Prove a document is the original
Fingerprint a signed contract or filing now, then re-check the token later to show it has not been altered since.
Show metadata was stripped safely
Separate content and metadata hashes prove that removing author or GPS data left the actual text and pages untouched.
A record you can defend
Download an evidence PDF and JSON sidecar that document the SHA-256 at a known moment — strongest alongside a trusted timestamp.
Three kinds of proof, three different questions
They look alike but do not answer the same thing. Here is which one you need when.
| Property | You are here Fingerprint | Proof package | Qualified timestamp |
|---|---|---|---|
| Answers the question | Does this version differ from that one, and in what respect? | Did this file already exist at that moment, and is it unchanged since? | Did this document already exist at that moment — and can the recipient see it straight away? |
| Where the proof lives | In a token and a JSON file you keep yourself. | In a separate ZIP alongside your document, verifiable offline. | Inside the PDF itself, as a PAdES DocTimeStamp. |
| When it is ready | Immediately. | Anchored in the daily run; requesting one stamps immediately. | Immediately. |
| Visible in Acrobat | No. | No. | Yes, green check mark. |
| Works on | PDF, Office, images and email with attachments. | Anything you convert here. | Any PDF you upload, including files from elsewhere. |
| Cost | 1 credit per file. | Included with the conversion; downloading needs a paid subscription. | 20 credits, paid account. |
Fingerprint You are here
- Answers the question
- Does this version differ from that one, and in what respect?
- Where the proof lives
- In a token and a JSON file you keep yourself.
- When it is ready
- Immediately.
- Visible in Acrobat
- No.
- Works on
- PDF, Office, images and email with attachments.
- Cost
- 1 credit per file.
Proof package
- Answers the question
- Did this file already exist at that moment, and is it unchanged since?
- Where the proof lives
- In a separate ZIP alongside your document, verifiable offline.
- When it is ready
- Anchored in the daily run; requesting one stamps immediately.
- Visible in Acrobat
- No.
- Works on
- Anything you convert here.
- Cost
- Included with the conversion; downloading needs a paid subscription.
Qualified timestamp
- Answers the question
- Did this document already exist at that moment — and can the recipient see it straight away?
- Where the proof lives
- Inside the PDF itself, as a PAdES DocTimeStamp.
- When it is ready
- Immediately.
- Visible in Acrobat
- Yes, green check mark.
- Works on
- Any PDF you upload, including files from elsewhere.
- Cost
- 20 credits, paid account.
They do not exclude each other: one document can carry a fingerprint, a proof package and an embedded timestamp at the same time.
Frequently asked questions
Why do two identical PDFs have different hashes?
Saving a PDF rewrites a hidden /ID value in the file trailer, even when nothing visible changes, so two content-identical PDFs return different SHA-256 byte hashes. That is normal, not tampering — the text and visual hashes ignore that wrapper and confirm the content is the same.
Is a hash proof that a document wasn't tampered with?
A matching hash proves two files are byte-for-byte identical, which is strong evidence of integrity. It does not prove who changed a file or when; hashes support authentication and are strongest combined with a trusted timestamp or signature.
Why SHA-256 and not MD5 or SHA-1?
Collisions in SHA-1 have been demonstrated — two different PDFs with the same SHA-1 exist — so it can't be trusted for evidence. SHA-256 is the current federal standard (NIST FIPS 180-4) and has no practical collision.
Can I fingerprint attachments inside an email?
Yes. Upload an .eml or .msg file and PDFengine fingerprints each node — the email and every attachment — so you can prove a single PDF buried in a thread is unchanged.
Is my file stored?
The file is processed to compute the hashes and handled under our retention policy; the fingerprint token and JSON sidecar are yours to keep so you can re-verify later without re-uploading.
How is this different from a qualified timestamp?
A fingerprint compares two versions and shows what changed: the bytes, the text, the rendering or the metadata. A qualified timestamp compares nothing but dates instead — it records that a document already existed at a given moment, and it is embedded in the PDF itself, where Adobe Acrobat shows a green check mark for it. In short: the fingerprint compares, the timestamp dates.
I already get a proof package with every conversion. What does a fingerprint add?
The proof package answers one question: did this file already exist at that moment, and is it unchanged since. That works on the raw bytes, so the moment someone re-saves the file it no longer matches — even when nothing changed in the content. The fingerprint splits that into four hashes, so you can show that only the packaging changed while text and rendering stayed identical. And it works on any file you upload, including documents that did not come from us.
Which of the three do I need?
To put two versions side by side and show where they differ: the fingerprint. To show that a document already existed at a given moment: the proof package that comes with your conversion. To have a recipient see that immediately when opening the file in Acrobat: the qualified timestamp. They do not exclude each other — a fingerprint from this tool is included in our daily anchoring run anyway, so you can download the timestamp token for it afterwards.
Comparing two files instead of one?
Use Compare to see, layer by layer, whether two documents are the same.