Proton

Proton AG is owned by the Proton Foundation (Fondation Proton), a Swiss non-profit foundation registered as CHE-418.863.304. The foundation became Proton AG's primary shareholder on 17 June 2024 and its binding purpose is, in its own words, 'to further the advancement of privacy, freedom, and democracy around the world.' The foundation can block hostile takeovers and Proton pledges 1% of net revenues to the foundation when conditions allow. Remaining shares are held by Proton employees, the Geneva innovation foundation FONGIT, and individual Proton users.

All user content -- mail, files, calendar entries, password vaults, VPN session data -- is stored on Proton-owned hardware in Switzerland. Proton's primary data centre is in Zurich. End-to-end encryption with zero-access architecture means Proton itself cannot read the content of user data; only metadata such as account creation time and the IP address used at registration is retained, and that metadata can be omitted by paying in cash. Region is not customer-configurable; Switzerland is the only jurisdiction.

Proton AG is Swiss-domiciled with no US subsidiary or US-headquartered parent -- the CLOUD Act does not reach Proton AG directly. However, several of Proton's commercial subprocessors are US-incorporated and handle limited operational data: Stripe, Chargebee and PayPal for payment processing; Zendesk for customer support; Calendly for sales meeting scheduling. None of these subprocessors have access to encrypted user content -- they only see the metadata necessary for their specific function. Article 271 of the Swiss Criminal Code additionally prohibits Proton from responding directly to foreign-authority requests that are not channelled through Swiss authorities.

Proton's canonical subprocessor list lives in section 3.1 of the Privacy Policy at https://proton.me/legal/privacy -- the Data Processing Agreement explicitly references this section as the controlling document. There is no standalone subprocessor page (/legal/subprocessors returns 404). The currently named subprocessors are Stripe, Chargebee, PayPal, Zendesk and Calendly, all handling payment or support data only.

Proton AG holds ISO/IEC 27001:2022 certification (initial certification May 2024, ANAB-accredited, three-year cycle with annual surveillance audits) and completed its first SOC 2 Type II attestation in July 2025, audited by Schellman. The compliance framework additionally covers GDPR, the revised Swiss FADP, HIPAA, CCPA, CJIS and PCI. Independent third-party code audits have been performed by Cure53 (most recent: Proton Pass, July 2023) and Securitum (most recent: Proton VPN no-logs audit, August 2025 -- the fourth consecutive annual review).

Yes. All Proton client applications are open source on two GitHub organisations: github.com/ProtonMail (Mail, Drive, Calendar, Bridge, mobile clients, plus the gopenpgp cryptographic library) and github.com/protonpass (Pass and the standalone Authenticator). The main clients are licensed under GPL-3.0; the cryptographic libraries (gluon, go-proton-api, go-crypto, pmcrypto, gopenpgp) are MIT or BSD-3-Clause. All clients have undergone independent third-party audits.