Proton VPN

VPN service with fully open source client apps

Open Source GPL-3.0 (client apps)

Overview

Proton VPN is operated by Proton AG, the Swiss company behind Proton Mail, and launched in 2017 out of the same team’s response to surveillance concerns that motivated Proton Mail’s own creation. Like Bitwarden in the password-manager space, Proton VPN follows an open-core model: the client applications across all platforms are published under the GPL-3.0 license and available on GitHub, while the underlying server infrastructure and hosted service remain a commercial operation funding the company.

Because the client code is public, Proton VPN’s apps have undergone independent third-party security audits, and Proton publishes transparency reports detailing government data requests. Proton VPN is also one of the few VPN providers offering a genuinely usable free tier — unlimited data, though with a smaller selection of free-tier server locations — rather than a time-limited trial. Being headquartered in Switzerland subjects the company to Swiss data protection law rather than the data-sharing agreements (like Five/Nine/Fourteen Eyes) some competitors’ jurisdictions carry.

Key Features

Open source clients — GPL-3.0 licensed apps across Windows, macOS, Linux, Android, and iOS, independently audited
Genuinely free tier — Unlimited data on a free plan, not just a time-limited trial
Secure Core servers — Routes traffic through hardened servers in privacy-friendly countries before exiting
NetShield — Built-in ad, tracker, and malware-domain blocking
Swiss jurisdiction — Operates under Switzerland’s strong data protection laws

Use Cases

Privacy-first VPN use — Verifiable client behavior via published source code and audits
Budget-conscious users — A genuinely usable free tier rather than a trial
Proton ecosystem users — Bundled with Proton Mail, Drive, and Pass subscriptions

Who It’s For

Proton VPN is aimed at users who want to verify the client software they’re trusting with their traffic rather than take a provider’s privacy claims on faith. It’s free with a limited server selection, with paid tiers unlocking the full server network and higher speeds.