Place of work: Pfäffikon SZ
Workload: 80–100%
Work start: from August 2025
Threema is the world’s best-selling secure messenger for both private users and businesses. Since 2012, we have been relentlessly committed to ensuring that our users can communicate without worrying about their privacy. Our growing user base includes millions of private customers and thousands of companies and organisations from all over the world.
Developing application protocols for interactions between mobile apps and backend services excites you? You’re interested in the security aspects of interaction flows? And you would call yourself an enthusiastic Rustacean? Then this position is right up your alley.
As an engineer in the protocols team, you will help us to further develop the core of Threema and contribute to the effective privacy protection of millions of people.
Build a deep understanding of the existing application and network protocols of the Threema ecosystem
Design and specify new application and network protocols
Implement protocol flows in “libthreema,” a Rust library that serves as the common core of future Threema apps
Develop “libthreema” bindings for Android (Kotlin), iOS (Swift) and desktop (TypeScript/WASM)
Perform code reviews within the development team
Experience with the design and implementation of network and application protocols
Extensive experience in software development, at least one year of practical experience with Rust
Enjoy high quality code (automated tests, linter, etc.)
Bonus points for experience with secure programming techniques, cryptography, protocol buffers, sans I/O, mobile apps, algorithms, and data structures
High level of awareness when it comes to security and privacy
Strong sense of responsibility and a careful way of working
Ability to analyze complex problems and contexts and find creative solutions
You can explain technical concepts clearly and precisely
You can break down requirements and long-term goals into clear work tasks
You are willing to familiarize yourself with new technologies and concepts and to keep learning
Good written and spoken German and English (at least B2 level)
We are also happy to accept applications from people who meet many but not all of these criteria.
A young, motivated team (±60 employees) with uncomplicated communication
Work-life balance: flexible working hours, option to work from home on up to two days per week, up to two workation weeks per year
Free budget for computer/workstation (macOS or Linux)
Public transport discount or parking space
Electric car charging facility
Free use of the company’s own fitness room incl. fitness trainer once a month
Ping pong table
Professional massage once a month
Portafilter machine with free coffee from a local roastery
Regular company events and after-work drinks
We look forward to receiving your application documents by email or via Threema:
To best process the applications we receive, we kindly ask you to include the following documents and information in your application:
CV
Salary expectations
Earliest possible starting date
We like to keep our application process pragmatic, with a compact assessment in which you work on a practical programming task lasting around three hours.
