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Electronic Signature

How to sign a PDF online?

Electronic signatures. Securely sign
Do you want to sign a PDF online that requires a legally binding digital or electronic signature?

It doesn’t matter if it is a consulting agreement, a freelance contract, or a power of attorney, or minutes of a board meeting, you can easily sign a PDF online with any of the many services that are available today.

Simply google, “sign pdf document online” and you’ll get more than a quarter of a billion hits.

The question is, which of these free online electronic signature services can you trust to sign a pdf document? What makes one more secure than others?

Before we go ahead and follow the instructions of this 90-second video on how to do so, it’s important that we discuss the different kinds of signatures, and more specifically, the difference between a digital signature and an electronic signature.

How to sign a PDF online

Signing PDF documents online is pretty straightforward. However, many first time users of PDF online signing might be cautious of uploading sensitive documents online which contains personal information such as contracts. That’s why we’ve listed a number of viable alternatives of electronic signature providers here.

It’s easy to sign a PDF document online. Here’s a step-by-step guide to how to achieve that:

  1. First of all, you create your document in PDF you want to sign from any document editor such as Google Docs or Microsoft Office Words. Simply create your contract you intend to sign and export as PDF.
  2. Add an explanatory name to your PDF document you want to sign and save it in your local drive.
  3. Choose one of the valid electronic signature providers here.
  4. Alternatively, you can create a free account in Oneflow here.
  5. Once you’ve created your free account, you’ll get an email from Oneflow to verify your email address. This is to make sure that no one else is signing you up without your permission.
  6. When you click on the link from the Oneflow email, you will have to complete your registration by filling in the required fields.
  7. Ta-da! You’re in. Now it’s time for you to get that PDF document signed.
  8. Choose “create new contract” and choose the “PDF template”.
  9. Upload the PDF document you want to sign to the template.
  10. Add the counterparty’s email address on the right panel and your contract is ready to send!
  11. You will be able to write a personal message, or add a personal video to the contract directly in Oneflow.
  12. When your counterparty receives, opens or signs the PDF contract you’ve just sent via Oneflow, you will automatically get a notification.
  13. Sign the contract and voilà! You’ve just sign a PDF document online with a legally binding electronic signature.
  14. The signed contract in PDF can be downloaded through the email automatically sent by Oneflow after it’s signed by all parties.

Watch the video below for a step-by-step demonstration of how to sign a PDF online

The difference between signing a PDF online with a simple electronic signature and digital signature

The terms digital signature and electronic signature are used interchangeably but they are actually very different things.

An electronic signature is electronic data that are logically connected to an electronic message of some sort, like a PDF document or a web contract, that the signatory wanted to sign.

Just like in the real world where a signature can take many forms, for example that in some countries an ink stamp is considered a legally binding signature, electronic signatures can take many forms.

An email reply with “I agree” can be considered an electronic signature. It’s just a very bad one!

So what is a good electronic signature? An electronic signature implemented by means of a digital signature!

A digital signature is a way to use advanced mathematics, involving the complex usage of really big prime numbers, to ensure both the authenticity and the origin of a message, document, or contract.

Like with electronic signatures, digital signatures can be made in many different ways. The most common way is to use Private Key Infrastructure, or PKI.

Read also: A basic guide on electronic signatures and what makes them legal?

Sign a pdf: Picture showing difference between electronic signatures and digital signatures

Digital signature using Private Key Infrastructure

To make a digital signature with PKI you use a certificate, which has been issued to the signatory by a certificate authority, or CA.

The CA is a specialized and trusted 3rd party whose responsibility it is to check that the signatory is who they say they are. 

The signatory uses their private key for the certificate to sign the document.

Anyone viewing the document can later use the public key for the certificate to verify that the document and the certificate.

As the signatory has sole control of the private while the public key is, well, publicly available it means that anyone can later verify who authored the document and that the document is unchanged.

It is this use of private and public keys that is called Private Key Infrastructure, or PKI, and it is the most common way to create electronic signatures.

But not all CAs are equal, some CAs are more secure and more trustworthy than others.

If a low-quality CA was used to issue the signatory’s certificate, you might have a hard time verifying that the signature is valid, or worse, the signatory might not be who the CAs say they are.

To ensure that it is easy to verify a signature, for example in Adobe Reader, only CAs that are either in the Adobe Approved Trust List (AATL) or the EU Trust List (EUTL) should be used.

The EU Trust List is regulated by eIDAS.

eIDAS and electronic signature

eIDAS, or electronic IDentification, Authentication and trust Services, is an EU regulation on electronic identification and trust services for electronic transactions in the European Single Market.

The highest level of electronic signatures and seals under eIDAS, the qualified electronic signature and qualified electronic seal, requires the use of a qualified certificate.

A qualified certificate can only be issued by a CA that has been certified as a Qualified Trusted Service Provider, or QTSP, by the EU. Any qualified certificate issued by a QTSP will automatically be part of the EU Trust List (EUTL).

Electronic seal

A seal is a special kind of electronic signature that allows legal entities, like an online contract signing service, to sign a contract.

This allows them to guarantee the origin and authenticity of the document to their customers, or in legal speak, to ensure “non-repudiation”.

Questions to ask before signing a PDF document online

As we previously mentioned, there are many free e-sign tools out there. Ones that you can upload your PDF, and send it for signing digitally.

With PLG (product led growth) being the go to market strategy for many SaaS companies, many of our competitors including ourselves offer free plans.

When it’s “free”, one might become suspicious of whether or not it’s legit.

Also what if you reach the limit of free PDFs you can sign, and you lose all your signed documents somewhere on the internet and you have pay to get access.

Here are some considerations before you electronically sign a pdf to figure out whether or not the free tool is legit or not:

  • Go with the tools with the most demanding enterprise clients. Because then they would have to fix their tools according to the strictest requirements
  • Go with the free tools with no limit on the PDF documents you can sign within a certain period. So that you don’t have to start to learn new tool again and again because you have reached your limit.

And it’s totally legit and safe because you’re forever protected by our ecosystem through our enterprise clients like Tele2, Miele, Northvolt, Experis Manpower, Systembolaget, to name a few.

Also, if you are looking to sign your PDF document online with secure, reliable signatures that can be verified even if the provider disappears from the Earth, then remember to ask these questions:

  • Is the document sealed from tampering with a secure digital signature?

What is the quality of that seal and can it be independently verified?

For many providers, the answer to both is “no”.  The reason is that proper electronic seals come with a price. For every digital certificate that is issued by a CA, there is a cost borne by the provider.

Sign and seal all your PDF contracts online

Oneflow is partnering with Sovos TrustWeaver to deliver a qualified electronic seal on all our contracts. Sovos TrustWeaver is a QTSP, in accordance with eIDAS. Something that can be easily verified by looking at the official EU Trusted List browser and is using only qualified certificates to seal our contracts.

For you, it means that the authenticity of a Oneflow contract can very easily be verified by opening it in Adobe Reader, or any other application that can read from the EU Trust List (EUTL).

The seal prevents intentional and accidental change of the PDF document after it was signed. This means you and your counterparties can remain secure in the knowledge that what you signed today will remain verifiably unchanged now and in the future, even if that is 20 years away.


How to sign a PDF document online?

With Oneflow, you can sign a PDF document online free with legally binding signatures.

  1. Create a free Oneflow account  here
  2. Upload your PDF
  3. Add a signatory
  4. Send for signing
  5. Ta-da!

What are digital contracts?

Digital contracts are contracts that are accessible online. Oneflow is a digital contract platform that turns your static contracts into dynamic ones. This makes contract data processable throughout the entire contract workflows from start to finish. Contract data can be seamlessly imported or exported across the different systems you use. Digital contracts make processes faster, decisions better, and deals quicker. It’s an easier, smoother, and smarter way for teams of all shapes and sizes to handle their contracts.

Why choose digital contracts over PDFs which I’m familiar with?

The PDF has come a long way since it was introduced in 1993 (almost 3 decades ago!) but it is still unfit for our data-driven world because the format itself is a completely static, ’dead’ document. Many ‘e-sign providers’ either add a layer of data fields on top of a PDF or use image recognition software to make it more useful.

No matter how many data fields you add, a PDF will never be fully interactive, and responsive. Digital contracts are dynamic, searchable, and can be processed to integrate with other business systems.

Are digital contracts safe?

Yes, and much safer than paper contracts! Security is at the core of everything we do. We are committed to keeping your most sensitive and critical documents secure. Find out more about security features, compliance, and reliability in Security Center.

GDPR compliance and data flow GDPR compliance and data flow

Ask us anything about truly digital contracts

Want to know more about digital contracts or the future of contract handling? We’d love to hear from you.


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