Electronic signatures: types, legality and how to sign

What is an electronic signature?

An electronic signature (eSignature) is any data in electronic form that a person uses to sign a document, from a typed name to a certificate-based signature. That is how the EU defines it in Article 3(10) of eIDAS, and the US ESIGN Act is just as broad: what counts is the intent to sign.

All types share that intent. What separates them is how well they prove who signed and that the document was not changed afterwards. The paper version is the wet (handwritten) signature.

What are the types of electronic signatures?

There are three types of electronic signatures under the EU’s eIDAS Regulation: the simple electronic signature (SES), the advanced electronic signature (AES) and the qualified electronic signature (QES). The UK kept the same three levels, and Switzerland uses a similar model in ZertES.

• Simple electronic signature (SES): a typed name, a drawn signature or a click. Example: an NDA.
• Advanced electronic signature (AES): linked to the signer’s identity, for example by a phone code or national eID. Example: a lease or a B2B loan.
• Qualified electronic signature (QES): issued by a qualified trust provider and equal to a handwritten signature across the EU. Example: a fixed-term employment contract in Germany.

The US has no levels. ESIGN and the state UETA laws give one broad definition and let the evidence (intent, consent, attribution, record integrity) decide whether a signature holds up.

Simple electronic signature (SES)

The simple electronic signature is the basic level: a typed name, a drawn signature or a ticked “I accept” box. The law sets no technical requirements, so the evidence comes from the platform’s audit trail. It suits everyday agreements such as NDAs, internal approvals and standard sales contracts.

Advanced electronic signature (AES)

An advanced electronic signature must be uniquely linked to the signer, identify them, stay under their sole control and make any later change to the document detectable (Art. 26 eIDAS). In practice, the signer confirms with a code sent to their phone or a national eID such as BankID or MitID. Use it for high-value B2B contracts, business loans, leases or new counterparties.

Qualified electronic signature (QES)

A qualified electronic signature is an AES based on a qualified certificate from a qualified trust service provider (QTSP), who checks the signer’s identity first, and created with a certified signature device (QSCD). Under Art. 25(2) eIDAS, it has the same legal effect as a handwritten signature in every EU country. Use it where the law requires written form, such as a fixed-term employment contract in Germany.

SES vs AES vs QES: what is the difference?

The table below compares the three levels under eIDAS.

Good to know: pick the lowest level that meets the legal requirement and the risk of the deal, because each step up means more effort for the signer.

Which type of electronic signature do you need?

Match the level to the document. These are typical choices in the EU; national form rules always win.

Acceptable forms and examples of electronic signatures

Acceptable forms of electronic signature include a typed name, a drawn signature, a scanned or photographed signature, a click-to-sign checkbox or clickwrap, a signature pad, a PIN or SMS code, and a certificate-based digital signature. Whether one is acceptable for a given document depends on the law that applies and the form that document needs.

Courts can be generous about what counts. In Canada, a 👍 emoji sent by text message was accepted as agreement to a contract (South West Terminal v Achter Land, upheld by the Saskatchewan Court of Appeal in 2024). They can also be strict: a German court held that a fixed-term employment contract with a scanned signature did not meet the written-form requirement, so the fixed term was invalid (LAG Berlin-Brandenburg, 16 March 2022, 23 Sa 1133/21). And in California, a name printed at the end of an email was not a signature, because there was no intent to sign the deal (J.B.B. Investment Partners v. Fair, Court of Appeal, 2014). The visual form matters less than the level and the form the law requires.

What makes an electronic signature legally binding?

In most countries, an electronic signature is legally binding. Under Art. 25(1) eIDAS, it cannot be denied legal effect in court solely because it is electronic, and national law decides which documents need a specific form. Courts look at:

• Intent: the signer meant to sign this document.
• Attribution: evidence of who signed, such as email verification, an SMS code or an eID.
• Integrity: the signed record is kept and shown to be unchanged, for example with an audit trail.
• Form rules: some documents need more, such as a QES for written form in Germany, or a wet-ink signature for wills and German employment terminations.

Whether electronic signatures are legally binding for a given document still depends on the country.

Which documents can you sign electronically?

Most business documents: employment contracts, NDAs, sales contracts, purchase orders, offer letters, leases, loan agreements and consent forms. The usual exceptions are wills, notarial deeds, real estate transfers and family law matters, set by national form rules rather than by eIDAS.

How to create an electronic signature

You can create an electronic signature with the tools you already use, or with an eSignature platform.

In Word, PDF, Google Docs and email

Word, PDF readers, Google Docs, Excel, Google Sheets and email clients all let you add a drawn, typed or image signature for free. Pick your tool for the steps:

Creating a digital signature online for free: draw or type your signature, or upload a photo of it on paper to cut it out of the background, then download a transparent PNG or SVG. Nothing is uploaded to a server. An image on its own is only an SES; an AES or QES needs an identity check.

With an eSignature platform

A platform adds what office tools leave out: identity checks for AES and QES, an audit trail, reminders and safe storage. In fynk:

1. Open the document from the email invitation. No account needed.
2. Click the signature field and draw, type or upload your signature. fynk saves it as your custom e-signature.
3. If the sender chose AES or QES, confirm with the phone code, your eID or the qualified provider.
4. Confirm. fynk records the signature in the audit trail.

How to send a document for electronic signature

To send a document for electronic signature, upload it to an eSignature platform, add the signers, place the signature fields and start signing. In fynk this is included in the Free plan, and you choose one of four signature types per document: simple (SES), advanced with a phone code (AES), advanced with a national eID such as BankID, MitID or ID Austria (AES), or qualified (QES).

1. Upload the document. PDF, Word and scanned contracts go in as they are, or start from a template.
2. Add the signatories by name and email.
3. Place the signature blocks where each person signs.
4. Start signing. Choose the signature type (simple, advanced or qualified) and, if needed, a signing order. Signers sign on any device, and fynk sends reminders.

When the last signature is in, fynk notifies everyone and stores the signed document with its audit trail, with the renewal date tracked in its contract management software. The signature methods directory lists every eID and provider behind its eIDAS-compliant eSignatures.

How to verify an electronic signature

Signer authentication happens before signing: email access for an SES, a phone code or eID for an AES, a QTSP identity check for a QES. Signature validation happens after signing: it checks that the signature is intact and the document unchanged.

To validate a signed document:

1. Open the PDF in Adobe Acrobat Reader and check the signature panel.
2. Upload it to the EU’s free DSS validator, which also reports whether it is an AES or QES.
3. Check the provider on the EU Trusted List for a QES.
4. Review the audit trail, the main evidence for simple signatures.

Manipulated signatures leave traces too, and signature forgery is easier to spot than most people think.

eIDAS 2.0 and the EU Digital Identity Wallet

eIDAS 2.0 (Regulation (EU) 2024/1183) entered into force on 20 May 2024 and keeps the SES, AES and QES rules. Every member state must offer an EU Digital Identity Wallet by 24 December 2026, and wallet users can create a QES free of charge for non-professional purposes. Banks and large platforms must accept it by December 2027. Germany plans its launch for 2 January 2027. More on the EUDI Wallet and qualified signatures and on eIDAS itself.

Electronic signature vs digital signature

An electronic signature is a legal concept (any data used to sign), while a digital signature is a cryptographic technique based on public key infrastructure (PKI). The software hashes the document, encrypts the hash with the signer’s private key, and anyone can check it with the public key in the signer’s certificate. If one character changes, the signature shows as invalid.

Every digital signature used to sign is an electronic signature, but not the other way round. The types of digital signatures follow the same levels: a certificate-based signature that meets Art. 26 is an AES, and one made with a qualified certificate on a certified device is a QES.

Is DocuSign an electronic or a digital signature?

Both, depending on the level. Platforms such as DocuSign, Adobe Acrobat Sign or fynk send most documents as an SES with an audit trail, and use certificate-based digital signatures for AES and QES. The better question is which eIDAS level the signing flow reaches.

Frequently asked questions

• What are the three types of electronic signatures?

  Under the EU's eIDAS Regulation, the three types are the simple electronic signature (SES), the advanced electronic signature (AES) and the qualified electronic signature (QES). They differ in how well they prove who signed: an SES needs no identity check, an AES is linked to the signer, and a QES is issued after a qualified identity check and equals a handwritten signature in the EU.

• What are the four types of signatures?

  People usually mean the handwritten (wet) signature plus the three electronic types: simple, advanced and qualified. In fynk, the advanced level comes in two forms, a phone code or a national eID, so senders choose from four electronic signature types.

• Is an electronic signature legally binding?

  In most countries, yes. In the EU and the US, a signature cannot be denied legal effect solely because it is electronic, and a qualified electronic signature equals a handwritten one across the EU. Some documents, such as wills or notarial deeds, still need a specific form.

• Are electronic signatures free?

  A simple electronic signature can be free: Acrobat Reader, Preview, Word and Google Docs all let you sign, and fynk's Free plan lets you send documents for signature. A qualified signature usually costs a fee from a trust service provider, although EU citizens will be able to create one for free with the EU Digital Identity Wallet for non-professional use.

• What is the most secure type of electronic signature?

  The qualified electronic signature (QES). The signer's identity is verified by a qualified trust service provider, the signature is created with a certified device, and any change to the document after signing is detectable. It is also the only type with the same legal effect as a handwritten signature in every EU country.

• Can electronic signatures be forged?

  A simple signature image can be copied, just like a wet signature can be imitated. Advanced and qualified signatures are much harder to forge because they are linked to a verified identity and any later change to the document is detectable.

• What is the difference between an electronic signature and an electronic seal?

  An electronic signature is created by a person and shows their intent to sign. An electronic seal is created by an organisation, such as a company, and proves the origin and integrity of a document like an invoice. eIDAS defines simple, advanced and qualified levels for both.