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How to Validate a Digital Signature in a PDF

by Hung Nguyen

You can also read this article in German, Spanish, French, Indonesian, Italian and Portuguese.

You can validate any digital signature using ordinary PDF readers. This article will explain how to do so.

As businesses start to migrate their work to the cloud, digital signing is becoming a common practice in the workplace.

Digital signing is a cryptographic process: A timestamp and a unique number are always assigned to a document, once signed.

If you have recently used our eSign tool or any other digital singing product—here’s how you can check for the validity of the signature. And although many PDF readers have this standard function, we’ll stick with one of the most common (free) one: Adobe Reader.

How to Validate a Digital Signature in a PDF Document

  1. Open the signed PDF file (with Adobe).

  2. Choose the ‘Signatures’ option on the left-hand panel (the fountain pen).

  3. Click the gray caret to open up a drop-down menu.

  4. Here, you can check the validity of the signature, along with other signature properties: the time of signing, the validity of the signer’s signature, and whether it’s been modified since the signature was applied.


How to validate any digital signature using a free PDF reader.

If a signature has not been validated, you can click ‘Validate All’ to start the process. Be warned; this may take a while for larger documents that contain multiple signatures.

Great! How Can I Sign a Document Digitally?


Smallpdf has one of the most potent PDF signing tools on the Internet. It’s free for anyone to create an electronic signature—and those with a premium account will have access to digital signing.

You may test the product out for free—see if you like the workflow, the signature quality, and the overall usability of our product. And if you are then tempted to upgrade the signatures to ‘digital,’ we always offer a seven-day free trial for you to get started—at no cost!

The process is relatively straightforward: Upload a document, create a signature, sign, and download!


Create a digital signature with Smallpdf, in less than a few seconds.

If you need to request a signature, it’s just one additional click to add a signer’s email and send them the document. In this case, we will notify you and the signer when you send out the request, when they sign the PDF, and when it’s near its deletion date (14-days).

Once you sign your documents digitally, you can go back to your Adobe Reader to validate the PDF’s digital signature, as illustrated above. Remember to always check in with your local laws on the legality of digital and electronic signatures in your country.

Is Smallpdf eSign Service Secure?


As secure as it can be!

Smallpdf caters to over 30 million trusted users every month. We remove files after one hour of processing and use SSL encryption for all file transfers. Our business is also ISO/IEC 27001 certified and GDPR compliant.

To make things even more practical, we prolong the period that we keep files online to 14 days—when you share files or request a signature.

There are also a few additional perks for Pro users. For instance, we will keep your signatures saved within the tool for a more streamlined signing experience.

If a signer has completed the signing process and does not want to keep the document online for the two-week period, you can go back to the main tool page, scroll further down, and full tracking of all signed documents. There is an X icon that you can click to remove individual signatures.

And better yet—we also offer file storage! Those who work on-the-go frequently can always access their documents, 24/7, whenever they are online. And with our suite of PDF tools, feel free to convert, compress, and modify your PDFs before signing them digitally.

Hung Nguyen
Hung Nguyen
Senior Growth Marketing Manager @Smallpdf