Radically simple digital signatures

What we do Use it

What we do

We digitally sign documents...

We make digitally signing documents extremely easy and convenient. Our mission is to increase the safety of contracts made through email.

...because you should use digital signatures

Making deals over email is dangerous. If you do, all protection you have is an email in your inbox and an email in your "Sent" folder. Unfortunately, none of them are irrefutable - the other side may claim they never got an email from you, may forge a fake email from you or may even claim that you forged the email from them. Email technology makes it often impossible to prove the other party wrong. In order to address these problems you should use digital signatures. We make it extremely easy.

Use it

Sign a PDF

To sign any number of PDFs, simply attach them to an email and send them to sign@mailwitness.com. We'll place a signature on each of them and send them back to you.

Sign email content

If you want to sign a simple piece of text, just send that text in an email to sign@mailwitness.com. Make sure the email has no attachments. We'll generate a PDF and send it back to you, so that you can sign it

Make multiple people sign a PDF

If you want to sign a document together with other people you need a PDF (you can easily generate one, as mentioned in the previous point). Once you have it you need to send an email with that PDF attached to all parties from whom you expect a signature and put sign@mailwitness.com in CC. You need to inform the recipients what they should do next, e.g. by embedding such a text in you email: "Hi, I would like you to sign the attached PDF(s). In order to do it, simply forward this email to sign@mailwitness.com. " Once all recipients forward the email to us, both you and the recipients will receive the document signed by all of you.

Why us

as easy as sending email

Send your document to sign@mailwitness.com and we will place a signature in your name on it and send it back to you.

EU residence

We operate under EU law and qualify as a Trust Service Provider according to the eIDAS regulation.


you don't need to create PDFs

You can send us a PDF or we can generate one for you - simply put the content in the e-mail and we'll send you the PDF.

we'll coordinate signing

We will coordinate collecting signatures from multiple parties. Send the PDF to the other parties, put sign@mailwitness.com in CC, let them forward your email to us and that's it's - all of you get the document signed by all parties

standard, verifiable signature

You don't need us to verify the signatures - standard software will (e.g. https://verifysignature.eu/ or Polish government verifier).

backdating protection

We implemented an innovative, blockchain-based backdating protection - nobody, not even us, can backdate the signatures. Learn more at https://opentimestamps.org/

we don't keep your data

We don't store your documents or emails. We have carefully designed our service to discard your email as soon as it is processed (usually a low number of seconds).

it's free

Last but not least - it's free! Test it out - send something to sign@mailwitness.com



  • Is the signature legally binding?
    Generally - yes, but this depends on your specific country regulations. The digital signature generated by mailwitness guarantees immutability, verifiability, cannot be reused between documents and is placed only after confirming one's identity via ensuring that they control the given email address.
  • How safe are the signatures?
    In short - as safe as your email with added guarantee of immutability and irrefutability. Mailwitness does not verify that the email address owner is who they claim to be (just like most of our competitors) - we verify that whoever had control over your email addresses made an explicit decision to sign the document. After the signature is generated, any change to the document will invalidate the signature.
  • How do you protect against email spoofing?
    We only sign a document in the name of the holder of the email address after having verified that the e-mail they sent us has a valid DKIM signature or after they have proven to us that they can also receive emails on the given address.
  • What is backdating protection?
    Whenever we sign a document in your name, we also initiate a process to put a small amount of opaque data into a Bitcoin transaction. When that transaction is made (usually after some hours), you receive an additional file from us. That file contains cryptographic information, which allows anyone to prove that your signature was placed before the mentioned Bitcoin transaction. Due to the nature of Bitcoin, nobody has the power to erase that from Bitcoin's history. You can read more about it at https://opentimestamps.org/.
  • Why does Adobe Reader show your signature as unverified?
    Generating signatures which would pass Adobe's verification is expensive. At this point we cannot afford paying for it and giving it away for free. We may create a paid version in the future which will pass Adobe's test. This does not make the signature less useful, though. In order to verify it, you can use other external services, e.g. https://verifysignature.eu/ or Polish goverment verifier.
  • How do I know that the person behind an email address is really who they claim?
    You need to establish it by yourself. There is no central email address book, so the appropriate way depends on the circumstances. You may verify it by phone, you may know it from previous interactions, you may just assume that the domain holder verified it (e.g. if it's a company email). In the future, we will likely add ways to address this, e.g. by adding support for using national electronic identity cards.

Contact Us

Mailwitness was founded, created and is supported by Unoperate.
We would love to hear from you at mailwitness@unoperate.com.
Please report any abuse to mailwitness-abuse@unoperate.com.