# Verify a signed document

> Check that a PDF signed through Vigilbase One is exactly the copy Vigilbase recorded, using the QR code or link on its certificate of completion.

Source: https://docs.vigilbase.com/one/billing/verify-a-signed-document

Every document signed through Vigilbase One ends with a certificate of completion. The certificate has a QR code and a link to a verification page at `https://one.vigilbase.com/public/verify/<reference>`. Anyone who holds the PDF can use it to check that the file has not been changed.

## Check a PDF

:::steps
1. **Open the verification page.** Scan the QR code on the certificate, or open the link printed next to it. The page shows the request's **Reference**, **Status** and when it was **Completed**.
2. **Add the PDF.** Drop the file on the page or select **Choose PDF**.
3. **Read the result.**
:::

The file stays on your device. Your browser calculates its SHA-256 fingerprint and only that fingerprint is sent to Vigilbase.

| Result | Meaning |
| --- | --- |
| **Authentic signed copy** | The file is byte for byte the signed PDF Vigilbase sealed, including the certificate of completion. |
| **This is the unsigned original** | The file is the document as sent for signature, before anyone signed it. |
| **Not a match** | The file differs from every copy Vigilbase recorded for this reference. It may have been edited, re-saved or printed to a new PDF. |

When the file matches, the page also shows the document's details, who sent it, and each signer with how they verified and when they signed. When it does not match, the page shows only the reference, status and completion date.

> [!TIP]
> Printing or re-saving a PDF changes its fingerprint, even if the text looks the same. Keep the file you downloaded from the signing email or page.

## Related

- [Sign a document](https://docs.vigilbase.com/one/billing/sign-a-document)
- [Contracts](https://docs.vigilbase.com/one/billing/contracts)