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Certify PDF Files

Nitro PDF Pro for Windows

Use certification to confirm that you are the author of a document and to control what changes are allowed.

When you certify a document, you define permitted actions. If a user makes a change that is not permitted, the certification becomes invalid.

Certification rules

    • A PDF can be certified only once
    • A certified PDF can be digitally signed multiple times, if permissions allow
    • If an unauthorized change occurs, the certification is revoked

Note: When you share a certified PDF, the viewer must support certification and digital signatures

Permitted actions

When you certify a document, select one of the following options:

    • Disallow any changes
      • Prevent all changes, including editing, commenting, form filling, and signing
      • If any change occurs, the certification becomes invalid
    • Allow form fill and signing
      • Allow form filling and signing only
      • Prevent all other changes
    • Allow commenting, form fill, and signing
      • Allow commenting, form filling, and signing
      • Prevent all other changes

        To certify a PDF

          1. On the Protect tab, in the Certify Document group, click Certify
          2. In the Certify Profile Wizard, select permitted actions
          3. Click Next
          4. Select a digital ID
          5. Select whether to show the certificate
          6. Click Next
          7. If the certificate is visible, click a location on the page
          8. In the Certify Document dialog, do the following:
            1. Select or enter a reason
            2. Select to save to the current file or a new file
            3. Select the certificate appearance
          9. Click Finish

          Document behavior after certification

          After certification:

            • The document allows only the selected actions
            • Other actions are not allowed
            • If an unauthorized change occurs, the certification becomes invalid

          Reasons to certify a document

          Use certification when you want to:

            • Confirm that you are the author of the document
            • Confirm the document content
            • Control allowed actions
            • Allow signing, form filling, or commenting without invalidating the certification

          Additional information

            • Certification helps protect document integrity
            • Certification can prevent actions such as editing text or inserting pages
            • Certification is different from a digital signature because it defines allowed actions

          Last updated: June 2026