SES, AdES and QES are the three electronic-signature levels defined by eIDAS. SES is any electronic mark of intent; AdES is uniquely linked to the signer and detects tampering; QES adds a qualified certificate and a qualified signing device, making it legally equal to a handwritten signature across the EU.
| SES | AdES | QES | |
|---|---|---|---|
| Legal effect | Admissible; weight judged case by case | Admissible; stronger evidential weight | Equal to a handwritten signature, EU-wide |
| Signer identity | Not required | Uniquely linked to the signer | Verified by a qualified provider |
| Tamper detection | Not required | Yes | Yes |
| Certificate | None | Usually a digital certificate | Qualified certificate |
| Signing device | None | Signer-controlled data | Qualified device (QSCD) |
| Typical use | Click-to-agree, typed name | Most business contracts | High-value & regulated signing |
Which level do you need?
For most commercial agreements, AdES is the practical default — strong, tamper-evident and widely accepted. Reach for QES when the law requires a handwritten-equivalent signature or when you need automatic cross-border recognition without arguing evidential weight.
Frequently asked questions
Is AdES legally valid in the EU?
Yes. An advanced electronic signature is admissible as evidence and cannot be rejected for being electronic. It simply does not carry the automatic handwritten-equivalence that a qualified electronic signature (QES) does.
See it on your own documents
Sealium tells you the exact signature level and format of any document you send — PAdES, CAdES, XAdES, JAdES, ASiC or KRX — in one API call. Free for 100 validations a month.
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