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Senior Rust Engineer (80-100%)

Salary: CHF 110'000 - 140'000 per year Requirements: 10+ years of professional software engineering experience, with at least 2 years writing Rust in productionSolid understanding of concurrency, memory management, and systems programmingExperience with distributed systems: what happens when a network partitions, a node dies, or a queue backs upComfort working close to the metal when needed, whether thats networking, storage engines, or protocol designExperience in working on scalable, low-latency, high-throughput systems.Good communication skills. Youll need to explain trade-offs to people who dont write RustA degree in computer science or equivalent experience. We care more about what youve shipped than where you studied Responsibilities: Design and build backend services in Rust that handle high-throughput, low-latency messaging trafficWork on core infrastructure: message queues, delivery guarantees, connection handling, and storage layersDebug and optimize systems under real production load, not just in benchmarksReview code and mentor other engineers on Rust patterns and systems designTake ownership of a service end to end, from design through deployment and maintenance Technologies: BackendHardwareLinuxmacOSNetworkRustSecurityNodeJS More: Threema is the worlds best-selling secure messenger for both private users and businesses. Since 2012, we have been working tirelessly to ensure that our users can communicate freely without worrying about their privacy. Our growing user base includes millions of private customers and thousands of businesses and organizations from all over the world.We are growing and looking for a new team member to join as aSenior Rust Engineer Backend (80-100%)The roleWere looking for a senior engineer to help design and build the core services behind our messaging backend. Youll work on the systems that handle message delivery, real-time presence, and end-to-end encryption at scale. Most of our backend is written in Rust, and were expanding it further.Youll join a small team of engineers who care about correctness, performance, and keeping things simple. Expect to write production code, review other peoples code, and have a say in architecture decisions from day one.What We Offer- A young, motivated team with straightforward communication- Flexible working hours, option to work from home up to two days per week- Option to work from anywhere for two weeks per year- Option to take unpaid leave- You can choose your own hardware (macOS or Linux)- Public transportation discount or parking space (electric car charging available)- Free use of fitness room, including a fitness trainer once a month- Professional massage once a month- Internal German or English courses- A great coffee machine ;-)- Regular company events and aperitifs- The good feeling of contributing to the effective protection of the privacy of millions of peoplePlace of work: Pfäffikon SZ (Greater Zurich Area)Start date: Immediately or by agreementHave we sparked your interest?We believe that diverse teams build better products. We welcome and encourage applications from people of all backgrounds, and perspectives. Your unique experience is an asset, and wed love to hear from you.Applications sent via email cannot be considered. Please use the official Apply button below so we dont accidentally miss your resume in our crowded inboxesFor agencies: we are filling this role directly and do not accept unsolicited candidate profiles. last updated 44 week of 2026

Zurich

CHF 110'000.00-CHF 140'000.00/year

Senior Applied Cryptography Engineer

Salary: CHF 120'000 - 150'000 per year Requirements: Degree in computer science, mathematics or information security, ideally with a focus on cryptography, or equivalent practical experienceSolid understanding of modern cryptographic primitives (AEAD, key exchange, KDFs, digital signatures) and of how they fail when combined incorrectlyWorking knowledge of key encapsulation mechanisms and of post-quantum cryptography, including hybrid constructions such as X25519MLKEM768Experience designing or reviewing security protocols, ideally in end-to-end encryption, key agreement or multi-device settingsYou write code yourself, in at least one of Rust, Kotlin, Swift, TypeScript or something comparableExperience reviewing implementations for side channels, nonce reuse, misuse-prone APIs and similar problemsYoure familiar with current frontier AI models and use them as a productivity multiplier in design work as well as in coding, for example to review specification drafts, survey recent literature, or poke holes in a protocol designWhatever tools you use, the outcome is yours. AI can draft and suggest, but the person accountable for a protocol that holds is youStrong sense of responsibility, precise way of workingYou can write a protocol specification that someone else can implement, and explain a cryptographic trade-off to people who are not cryptographersPragmatic judgment about when a design is good enough to ship and when it is notWillingness to have your own designs picked apart, and to pick apart other peoples with careGood written and spoken English (at least B2)German is a nice-to-have Responsibilities: Develop and specify cryptographic communication protocolsDesign cryptographic systems, such as key management and multi-device synchronizationLead Threemas migration to quantum-safe cryptography, together with the cryptography researchers at IBM ResearchOwn threat modeling for new product features and protocol designs, in close collaboration with the product and engineering teamsAnalyze protocols, algorithms and implementations for security weaknesses, and assess what new attack vectors mean for our productsAssess the vulnerability reports that reach us through our bug bounty partner and coordinate the fix with the engineering teamsFollow current developments in applied cryptography and turn relevant findings into concrete product improvementsMaintain contacts with the security research community and, if you enjoy it, represent Threema at conferences Technologies: AICryptographyHardwareIBMKotlinLinuxmacOSRustSecuritySwiftTypeScript More: Threema is the worlds best-selling secure messenger for both private users and businesses. Since 2012, we have been working tirelessly to ensure that our users can communicate freely without worrying about their privacy. Our growing user base includes millions of private customers and thousands of businesses and organizations from all over the world.We are growing and looking for a new team member to join as aSenior Applied Cryptography Engineer (80 - 100%)Your RoleAs an applied cryptography engineer at Threema, you will help us design, build and scrutinize the cryptographic protocols behind our messenger, and contribute to the effective privacy protection of millions of people.What We Offer- A young, motivated team with straightforward communication- Flexible working hours, option to work from home up to two days per week- Option to work from anywhere for two weeks per year- Option to take unpaid leave- You can choose your own hardware (macOS or Linux)- Public transportation discount or parking space (electric car charging available)- Free use of fitness room, including a fitness trainer once a month- Professional massage once a month- Internal German or English courses- A great coffee machine ;-)- Regular company events and aperitifs- The good feeling of contributing to the effective protection of the privacy of millions of peoplePlace of work: Pfäffikon SZ (Greater Zurich Area)Start date: Immediately or by agreementHave we sparked your interest?We believe that diverse teams build better products. We welcome and encourage applications from people of all backgrounds, and perspectives. Your unique experience is an asset, and wed love to hear from you.Applications sent via email cannot be considered. Please use the official Apply button below so we dont accidentally miss your resume in our crowded inboxesFor agencies: we are filling this role directly and do not accept unsolicited candidate profiles. last updated 44 week of 2026

Zurich

CHF 120'000.00-CHF 150'000.00/year

WebRTC Engineer (100%)

Salary: CHF 120'000 - 160'000 per year Requirements: 5+ years of software engineering experience, with at least 3 years working directly on WebRTC or other real-time media systems.Deep understanding of the WebRTC stack: SDP, ICE, DTLS, SRTP, and how they fit together in practice.Experience building or operating an SFU or MCU, whether custom or based on open-source projects such as mediasoup, Janus, Jitsi, Pion or LiveKit.Solid knowledge of audio and video codecs (Opus, VP8, VP9, AV1, H.264) and their trade-offs.Strong skills in at least one of C++, Kotlin, Go or Rust, plus comfort with TypeScript/JavaScript for browser-side work.A methodical approach to debugging distributed, latency-sensitive systems where the root cause might be the network, the device or the code.Clear communication and the ability to explain complex media problems to people outside the team. Responsibilities: Build and improve the WebRTC media pipeline across web, desktop and mobile clients, including audio, video, screen sharing and data channels.Develop and scale our Selective Forwarding Unit (SFU) and signaling services to support large meetings, webinars and breakout rooms.Tune congestion control, bandwidth estimation, simulcast and SVC layer selection so calls adapt gracefully to poor networks.Own call quality end to end: define metrics, build dashboards, investigate issues using getStats, RTC event logs and packet traces, and ship fixes.Work on NAT traversal and connectivity, including STUN/TURN infrastructure, ICE behavior and fallbacks for restrictive corporate networks.Collaborate with client, backend, security and product teams on features like recording, live captions, noise suppression and end-to-end encryption.Review code, mentor other engineers and help set technical direction for the real-time stack. Technologies: BackendHardwareSupportJavaScriptJitsiKotlinKubernetesLinuxmacOSMobileNATNetworkRustSecurityTypeScriptWeb More: Threema is the worlds best-selling secure messenger for both private users and businesses. Since 2012, the company has been working tirelessly to ensure that users can communicate freely without worrying about their privacy. Its growing user base includes millions of private customers and thousands of businesses and organizations from all over the world.The company is growing and looking for a new team member to join as a WebRTC Engineer (100%).The role is hands-on and involves ownership of the real-time media stack, including native clients, the web browser and SFU infrastructure. The position focuses on stable large meetings, crisp screen sharing at low bandwidth, and reducing join times so meetings start immediately.What We Offer:- A young, motivated team with straightforward communication- Flexible working hours, option to work from home up to two days per week- Option to work from anywhere for two weeks per year- Option to take unpaid leave- You can choose your own hardware (macOS or Linux)- Public transportation discount or parking space (electric car charging available)- Free use of fitness room, including a fitness trainer once a month- Professional massage once a month- Internal German or English courses- A great coffee machine ;-)- Regular company events and aperitifs- The good feeling of contributing to the effective protection of the privacy of millions of peoplePlace of work: Pfäffikon SZ (Greater Zurich Area)Start date: Immediately or by agreementApplications sent via email cannot be considered. Please use the official Apply button below so they dont accidentally miss your resume in their crowded inboxes.For agencies: the role is filled directly and unsolicited candidate profiles are not accepted.The company welcomes and encourages applications from people of all backgrounds and perspectives. last updated 44 week of 2026

Zurich

CHF 120'000.00-CHF 160'000.00/year

Protocol Stack Engineer (80 – 100%)

Salary: CHF 110'000 - 140'000 per year Requirements: At least 6 years of software engineering, with several years working on network or cryptographic protocols.A solid grasp of applied cryptography. You know how authenticated encryption, key exchange, forward secrecy and post-compromise security work, and where implementations usually go wrong.Experience reading and writing protocol specifications precise enough for someone else to implement from.Strong skills in at least one systems language. Rust is a plus.Care about the details. In this job, a missing length check is a vulnerability.Good written English. German is helpful but not required.Strong sense of responsibility, precise way of workingYou can write a protocol specification that someone else can implement, and explain trade-offs to people who are not protocol specialistsPragmatic judgment about when a design is good enough to ship and when it is notWillingness to have your own designs picked apart, and to pick apart other peoples with careGood written and spoken German and English (at least B2) Responsibilities: Design new protocol features and extensions, such as multi-device sync, group messaging and calls, and write the specifications for them.Implement protocol logic in Rust and review implementations across our Android, iOS, desktop and web clients.Model threats and reason through edge cases like message reordering, device loss, malicious servers and compromised keys.Work with external security researchers and auditors, respond to findings and ship fixes.Keep backward compatibility for a large installed base while moving the protocol forward.Mentor other engineers and help set standards for how we write and review security-critical code. Technologies: AIAndroidCryptographyHardwareLinuxmacOSMobileNetworkRustSecurityWebiOS More: Threema is the worlds best-selling secure messenger for both private users and businesses. Since 2012, we have been working tirelessly to ensure that our users can communicate freely without worrying about their privacy. Our growing user base includes millions of private customers and thousands of businesses and organizations from all over the world.We are growing and looking for a new team member to join as aProtocol Stack Engineer (80 – 100%)Your RoleThe protocols underneath all of this are what were hiring for. Youll design, implement and maintain the cryptographic protocols that carry every Threema message, including Ibex, our forward-secrecy protocol. Your work will be read by our own engineers and also by outside researchers, auditors and curious users. We expect it to hold up to that.What We Offer- A young, motivated team with straightforward communication- Flexible working hours, option to work from home up to two days per week- Option to work from anywhere for two weeks per year- Option to take unpaid leave- You can choose your own hardware (macOS or Linux)- Public transportation discount or parking space (electric car charging available)- Free use of fitness room, including a fitness trainer once a month- Professional massage once a month- Internal German or English courses- A great coffee machine ;-)- Regular company events and aperitifs- The good feeling of contributing to the effective protection of the privacy of millions of peoplePlace of work: Pfäffikon SZ (Greater Zurich Area)Start date: Immediately or by agreementHave we sparked your interest?We believe that diverse teams build better products. We welcome and encourage applications from people of all backgrounds, and perspectives. Your unique experience is an asset, and wed love to hear from you.Applications sent via email cannot be considered. Please use the official Apply button below so we dont accidentally miss your resume in our crowded inboxesFor agencies: we are filling this role directly and do not accept unsolicited candidate profiles. last updated 44 week of 2026

Zurich

CHF 110'000.00-CHF 140'000.00/year