Tuta Calendar

Tuta Calendar is the calendar half of Tuta’s encrypted suite, included free with every Tuta account. Events, invitations and shared calendars are end-to-end encrypted, and Tuta describes the encryption as quantum-safe under a zero-knowledge architecture, so the provider cannot read event titles, times or participants. Push reminders are delivered without exposing event contents to a third party.

Apps cover Android and iPhone, with open-source desktop clients for Windows, macOS and Linux. Calendars and individual events can be shared with other users, and two-factor authentication protects the account. The practical cost of the encryption model is interoperability: this is a closed calendar rather than one that federates with an existing Google or Microsoft stack.

Tutao GmbH is registered at Deisterstr. 17a, 30449 Hanover, at the district court of Hanover under HRB 208014, VAT ID DE280903265. Arne Möhle, Hanna Bozakov and Matthias Pfau are the managing directors. Möhle and Pfau founded the company in 2011, and the service traded as Tutanota until the rename on 7 November 2023.

There is no investor above the founders. Tuta says it built the service on long-term loans rather than venture capital, repaid them in full, and has been profitable since 2016 on subscription revenue alone. The team works from offices in Hanover and Munich.

Tuta owns its server hardware and keeps it in ISO 27001-certified data centres in Germany, so the company and the stored mail sit under the same German and EU law. It reports more than 10 million accounts and more than 10,000 business customers. The clients have been open source since 2014, and Tuta describes itself as the first end-to-end encrypted mail service to ship quantum-resistant cryptography, in its TutaCrypt protocol.