EU law defines three levels of electronic signature. swipesign issues the top two: Advanced (AES) and Qualified (QES). Both are legally valid, and both seal the document so later changes are detectable.
Where they differ, and it is the whole difference, is how sure anyone can be that the signer was who they claimed to be.
How each identifies the signer
AES uses indirect identification. The signer is identified by the email address the document was sent to, and by SMS to their phone number where one is supplied. Nobody checks an ID document. swipesign describes it in the app as a medium legal standard with limited, indirect signer identification via phone number or email domain.
QES uses qualified identification. The signer authenticates through a qualified trust service provider, a national eID, or a one-off online identity check against a government-issued document. A qualified certificate is issued in their name. See Our trust service providers.
| AES | QES | |
|---|---|---|
| How the signer is identified | Indirectly: email address, plus SMS if a phone number is given | Qualified check by a trust service provider |
| ID document examined | No | Yes, or an existing national eID |
| Tamper-evident | Yes | Yes |
| Standing in the EU | Admissible and evidenced | Equivalent to a handwritten signature |
| If disputed | You show your evidence | The challenger has to prove it wasn't them |
| Effort for the signer | Almost none | A few minutes the first time |
Phone numbers make AES stronger
Because AES leans on indirect signals, the ones you give it matter. Add a phone number for each signer and identification rests on something they physically hold. Leave it out and it rests on email alone: the app flags exactly this, warning of a Weak AES when signers have no phone number.
Which to use
Use AES where you already know and trust the counterparty and the document is routine: an NDA with a regular client, an internal approval, an order confirmation. It is fast because it asks almost nothing of the signer.
Use QES where identity is the thing that matters: a first-time counterparty, a high-value agreement, anything a regulator will look at, or anywhere national law requires the written form. QES is the only level that is automatically equivalent to a handwritten signature and that shifts the burden of proof.
You choose per document when you build the workflow, so it is not tied to your account or plan.