Senior .Net/C# Developer (Windows)

Job description

We are looking for enthusiastic .Net & C# Developers to join our product teams. Currently, there are vacancies with both the ProtonVPN and ProtonDrive.


The ProtonDrive team is creating a new, secure online storage system that brings Proton privacy and security to cloud storage. ProtonDrive will be available for all major platforms. As a member of the ProtonDrive team, you will help build the native Windows client and improve the app’s stability and performance.


The ProtonVPN team wants to offer our users the best VPN experience possible by building a secure product that is easy to use, stable, and fast. As a member of the team, you will improve and extend the ProtonVPN applications by building user interfaces, optimizing network protocols, and creating Windows kernel drivers.


Your responsibilities

  • Analyze the complex issues that arise from building apps for the Windows system, its networking stack, and other unforeseen issues
  • Develop innovative solutions to improve the interface, usability, connectivity, stability, performance, and resilience of applications
  • Extend existing open source projects or create new ones
  • Collaborate extensively, both with members of the ProtonVPN team and with others in the company

Job requirements

  • Expert-level knowledge of Windows development, with a focus on desktop/client development
  • Excellent knowledge of the C# ecosystem
  • A documented track record of contributions to multiple Windows projects and applications
  • Strong software engineering skills (development, testing, performance analysis)
  • Knowledge of the networking stack (especially on the Windows environment)

Bonus points for ProtonDrive if you have:

  • Knowledge of distributed systems
  • Knowledge of cryptography
  • Knowledge of file systems and related APIs
  • Knowledge of POSIX API

Bonus points for ProtonVPN if you have:

  • Knowledge of Windows Kernel driver development
  • Knowledge of VPN protocols such as OpenVPN, IKEv2 or WireGuard
  • Experience with Windows system administration
  • Experience debugging and profiling code
  • HTTPS certificates and public key infrastructure
  • Experience developing open-source software



Why you should join Proton

  • We work on interesting, challenging problems every day. There is never a dull moment.
  • Our startup culture means everyone’s opinion matters. You can have a significant impact.
  • Our rapid growth means there are many opportunities for advancement.
  • The chance to do something meaningful. Proton products protect dissidents, journalists, and activists. Our work saves lives.
  • Be part of something bigger. Millions of people and businesses around the world have embraced our idea of an Internet where privacy and security are the default. Join the privacy revolution that is changing the world.

Proton uses the Recruitee recruitment platform for a better hiring experience for the candidate. Your data will be kept confidential. It is not shared with any third parties.

Keep in mind that you will receive emails from careers@protonmail.recruitee.com or other addresses on the protonmail.recruitee.com domain.




Our company

Our mission is to defend human rights and democracy through building software that is essential for digital freedom and privacy protection for all Internet users.

ProtonMail was founded in 2014 by a group of scientists who met at the European Organization for Nuclear Research (CERN). And since its inception, the company has grown at a fast pace and today has over 26 million users. Our principal product, ProtonMail, is the world’s largest secure email service. Our second product, ProtonVPN, is one of the world’s most popular VPN services. Our vision is to build an Internet platform for the protection of digital rights, and we are also developing additional products such as ProtonCalendar, ProtonDrive, and much more.

Proton users include leaders of the Hong Kong protest movement, New York Times journalists, some of the world’s largest corporations, and millions of ordinary citizens from over 180 countries. Our team is diverse and dynamic, representing over 30 different nationalities, with offices in Geneva, Zurich, Prague, Vilnius, Skopje, San Francisco, and Taipei.