How to sign a PDF with AutoFirma

AutoFirma is the Spanish Government's free application for signing documents with a digital certificate or the DNIe (Spanish electronic ID card). Many procedures with the public administration ask for it. We explain how to use it and when something simpler will do.

MultiDocs team2 min readUpdated on 29 October 2026With official sources

In 30 seconds

  • Only download AutoFirma from the Government's official website (firmaelectronica.gob.es).
  • You need a digital certificate installed, or the DNIe with a card reader or a phone with NFC.
  • For everyday documents that aren't official procedures, a finger signature is usually enough.

Before you start

  • A digital certificate installed on your computer (for example, the FNMT personal certificate) or your DNIe with a card reader. We explain how to get one in signing with a digital certificate.
  • AutoFirma installed. It's a free download from the Government's official electronic signature portal (firmaelectronica.gob.es), with versions for Windows, macOS and Linux.

Official data

1.9

is the AutoFirma version for Windows on the official website (1.9.2 for Macs with an M1 processor or later).

Source: firmaelectronica.gob.es, 29-10-2026
80.7%

of people in Spain aged 16 to 74 dealt with the public administration online in the last year.

Source: INE, 2025
41.2%

downloaded or printed an official form online in the last year.

Source: INE, 2025

Signing a PDF with AutoFirma

  1. Open AutoFirma and click the button to select the file you want to sign.
  2. Choose the PDF. AutoFirma recognises the type of document and picks the right signature format.
  3. If you want the signature to be visible on the document, tick the visible signature option and draw the box where it should appear.
  4. Click “Firmar” (Sign) and choose your certificate (or enter your DNIe PIN).
  5. Save the signed document. AutoFirma suggests a new name so the original isn't overwritten.

How to check the signature

You can open the signed PDF in Adobe Acrobat Reader, which shows the signature panel, or check it on VALIDe, the Spanish administration's validation service.

Do I always need AutoFirma?

No. AutoFirma creates a certificate-based signature, which is what some official procedures require. For everyday use (permission forms, quotes, simple contracts, school documents) an electronic signature made with your finger or mouse is enough, and it's also valid under the European eIDAS regulation. We explain the difference in digital signature and electronic signature.

Common problems

  • My certificate doesn't show up: check that it's installed in the system or browser certificate store and that it hasn't expired.
  • The DNIe isn't recognised: check that the reader is connected and that you've installed the electronic ID card software.
  • A public body's website won't open AutoFirma: close and reopen your browser after installing it.

Frequently asked questions

Is AutoFirma free?

Yes. It's a free application from the Spanish Government.

Can I sign with AutoFirma without a certificate?

No. AutoFirma needs a digital certificate or the DNIe. If you don't have one, you can sign with your finger on MultiDocs: it's a valid electronic signature for most documents.

What signature format does it use for PDFs?

For PDFs it usually applies a PAdES signature, which is embedded in the document itself.

Official sources

We checked each source on 29 October 2026. If you spot outdated information, email us at info@multidocs.es.

More guides

Signing with a certificateHow to sign a document with a digital certificateHow to get one and sign a PDF with it.Signing with a certificateHow to sign a document with the DNIeReader, PIN and AutoFirma, step by step.Signing with a certificateHow to sign documents with Cl@veFor procedures with the public administration.