The SMB’s compass to digitalization  

2 min

Updated on Sept 4, 2023

Published on Jul 6, 2022

Why is creating a signature in .png format not an ideal solution?

Illustration signature format png
Zaki Micky

Zaki Micky

Brand & Content Manager

Illustration: Mélusine Vilars


Imagine that you’re preparing to sign a contract in PDF format after finally reaching an agreement or that you are due to attend the most important job interview of your life but the company asks you to complete the online signature of some documents on processing your personal data.

In these fairly ordinary, everyday situations, there is one question you should ask yourself: “So, how am I going to sign this document online? ”. At this point, many users would be tempted to add their signature to the PDF document in .png format: a solution that is not always (almost never!) ideal.

What is the .png format? Why does it seem suitable when you want to create a digital signature?

Png is a copyright-free picture format that is suited to on-screen display, especially for the web.

Creating a .png file seems to be a very practical solution for online signatures: it can be created by scanning your signature written on a paper document or by using a computer mouse, a touch-sensitive keypad or even a tablet (graphic or not) to draw it on screen.

The .png format therefore appears to be appropriate for anyone who want to obtain an image of their own signature. There are three major reasons for this:

  • IIt is capable of saving images without losing any information.
  • This format lets you create a transparent background (and therefore more aesthetically appealing signatures) 
  • It is now supported by the main graphic and PDF editing software (from Photoshop and Illustrator to PDF reader-editors such as Acrobat Reader, as we will see in the next paragraph!).

Is it possible to insert a .png format signature in a PDF file?

Yes, it is possible to insert a .png format signature in a PDF file and there are several specific programmes that will help you do this. Acrobat Reader – the most common of these programmes – comes with a dedicated function for the signature of PDF documents. 

The “Fill & Sign” function lets you add your signature and then your name using your keyboard, select a font and save your preferences to generate the png image of your signature. Once you have completed this stage, your picture format signature remains accessible and you can add it to your document just by clicking on the signature space provided.

Other programmes also support the inclusion of .png format signatures in PDF files and other electronic documents. This is true, for example, of Nitro Pro and Preview (on macOS).

Signature in .png format: aesthetically appealing, but with no legal value.

Inserting a .png image of your signature in PDF documents is undoubtedly an excellent solution from a graphic and aesthetic point of view... HOWEVER, please note: signatures in .png format have no legal value! 🚨

These signatures are simply pictures, no more, no less. In other words, their creation does not involve the use of encryption tools capable of guaranteeing the authenticity, integrity and legal value of the signature, as required by the eIDAS regulation

Signing a PDF document with legal significance: signature in .png format vs electronic signature

Among the various types of digital signature available, an electronic signature is the only one that enables you to add a signature with full legal value to a PDF: compared to a simple signature in .png format, an electronic signature – created using a specialist solution such as Yousign – includes a “cryptographic protocol” that is automatically generated during creation of the signature to ensure its legal value.

Acrobat Reader can nonetheless prove useful, because it helps to determine whether a document has been signed electronically or if an image has simply been added. It can therefore be used to check the legal value of the signature.

💡When opening the file in Acrobat Reader, a green tick is visible when all of the signatures have been added using a legally-valid electronic signature tool.

Yousign’s electronic signature solution: just as aesthetically appealing as a .png format signature and fully legally valid!

Guaranteeing the legal value of a signature added to a PDF document does not necessarily mean abandoning the aesthetic appeal of a png format signature.

The electronic signature offered by Yousign combines these two aspects: our solution ensures the signature is legally binding and creates an encryption key that will be automatically inserted in the PDF document, whilst also generating a png image of a handwritten signature that will be subsequently integrated into the file.  

Start your
free 14-day trial

15 000+ growing SMBs trust Yousign to sign their documents

green arrow
cta illustration

Try Yousign for free for 14 days