Tresorit eSign is the electronic-signature module of Tresorit AG (Pfingstweidstrasse 60b, 8005 Zurich; CHE-349.825.210), the zero-knowledge end-to-end-encrypted cloud-storage company that has been a wholly-owned subsidiary of Swiss Post (the Swiss state-owned postal and digital-services operator) since 2021. Launched as a product around 2022, eSign is the directory's only e-signature listing that combines genuine zero-knowledge, end-to-end encryption of the document workflow with full eIDAS Qualified Electronic Signatures (QES). Tresorit is not itself a Qualified Trust Service Provider; the QES tier is issued through a partnership with Evrotrust, an EU-listed QTSP (Bulgaria), and obtaining a qualified signature requires ID/passport plus video identification of the signer, in line with eIDAS. The product also offers simple electronic signatures, Long Term Validation (signature validity guaranteed for 5, 10, or more years), drag-and-drop fillable fields, and signing from any device without a Tresorit account.
For an EU-sovereignty audit the posture mirrors Tresorit's storage listing. The infrastructure is Microsoft Azure, with the default data-at-rest region in Ireland (EU) and customer-selectable EU residency (Germany, France, Netherlands and others) on Business and Enterprise plans; the company is ISO/IEC 27001:2022 certified (TÜV Rheinland) and aligned with GDPR plus a broad regulated-industry set. The directory records cloud_act_exposure: material because Azure is a US-owned hyperscaler sitting in the at-rest path, but the zero-knowledge architecture means Azure stores ciphertext only and Tresorit holds no keys, so compelled disclosure yields no readable content. The two transparency gaps carried over from the storage listing apply here too: there is no public standalone DPA URL (the DPA is delivered to business customers on request) and the sub-processor list is published via the Tresorit help centre rather than a dedicated legal page. Ownership is Swiss-state-anchored (ownership_signal: other: Switzerland, with Swiss Post as sole shareholder).
Pricing is paid: licences are around €5/month per user, with per-signature pricing of roughly €0.3 for a simple electronic signature and €2.5 for an EU Qualified electronic signature, and a small free quota (about 10 simple and 6 qualified signatures) for evaluation. Best fit: regulated teams (legal, healthcare, finance, security-conscious businesses) already standardised on Tresorit's encrypted storage who want qualified signatures inside the same end-to-end-encrypted workspace rather than bolting on a separate signing platform. Buyers whose priority is the cleanest ownership-and-sub-processor story for purely-EU workflows should look to Skribble (Switzerland, no CLOUD Act exposure); the Namirial-group QTSPs Universign (France) and Signaturit (Spain), once the benchmark here, now carry the same material exposure (AWS at rest) plus a US-private-equity parent (Bain Capital, 2025) and, unlike Tresorit eSign, no zero-knowledge encryption to offset it. Tresorit eSign's differentiator remains the zero-knowledge-encryption-plus-QES combination, which none of the other listed options match.