Windows System Developer / C# Software Developer

Job description

At Proton, we envision an internet where privacy is the default, and we’re building ways to help all people secure their digital lives and take control of their data. 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 40 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, including ProtonCalendar, ProtonDrive, and more to come.

Our users include New York Times journalists, some of the world’s largest corporations, and millions of ordinary citizens. The world is adopting our products at an accelerating pace. Whether it’s in New York, or at the front lines of the global struggle for freedom and democracy in Hong Kong, Belarus, and Myanmar, the work we do saves lives and is transforming the world. Our team is diverse and dynamic, representing over 30 different nationalities, with offices in Geneva, Zurich, Prague, London, Vilnius, Skopje, and Taipei, employing people across the world.

Proton is a mission driven company. We’re deeply committed to enabling freedom online and ensuring the internet serves the interests of all people. Our technologies provide trusted ways for people to be secure online and in control of their information at all times. The world is adopting our products at an accelerating pace. Help us bring it from tens of millions of users, to billions of users. We’re creating one of the world’s most impactful tech companies.

What you will do
You would be joining the ProtonVPN Windows team and be responsible for creating our native client for the Windows platform. Within the team, you would be the reference expert for system-level development needs e.g. linked with Windows driver development, Windows firewall, and the corresponding network stack. You can also expect to participate in development of components and features in C#.

  • 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 system development

  • Excellent knowledge of the C/C++ and C# ecosystem

  • A documented track record of contributions to multiple Windows projects and applications

  • Experience in creating Windows kernel drivers

  • Strong software engineering skills (development, testing, performance analysis)

  • Knowledge of the networking stack (especially in the Windows environment)

  • 4+ years of relevant working experience

Bonus points for

  • Contributed to open-source projects

  • Mastered Win32 API

  • Active Windows Networking stack experience

  • Team leading skills


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.


ProtonMail uses the Recruitee recruitment platform for a more effective hiring process and a better candidate experience. Your data will always be kept confidential and is not shared with any third parties. Keep in mind that you will receive emails from the email address careers@protonmail.recruitee.com or other addresses on the protonmail.recruitee.com domain.


Proton does not accept unsolicited resumes from any sources other than directly from a candidate. Proton will not pay a fee for any placement resulting from the receipt of an unsolicited offer, even in a situation when the relevant candidate is employed by Proton.