Senior Software Engineer

About Certonymity

Certonymity is developing the next generation of secure communication technology. Our mission is to make encrypted email simple and widely accessible by combining advanced cryptography with real-world identity verification.

Our first product, C.Email, enables users to send and receive fully end-to-end encrypted messages without depending on third parties or complicated configurations. Each user has a verified digital identity, connected to their passport yet kept completely private through cryptographic keys — maintaining anonymity while ensuring accountability.

We are an ambitious, self-funded start-up with founders who have backgrounds in AI, Hedge Funds, Biotech, and Energy Production. Headquartered in London, our technical team is distributed across the UK and France. Working independently allows us to move quickly, innovate freely, and stay focused on creating cutting-edge cryptographic, blockchain, and mobile-first privacy tools.

About the Role

We're seeking a Senior React Native Engineer to help build, refine, and scale our encrypted email application, C.Email. You'll collaborate closely with our CTO, cryptography expert, and engineering team to deliver a secure, intuitive, and high-performing product. This is a hands-on role with full ownership of features — from development and testing through to deployment and user experience improvements. Your work will directly influence how millions of people communicate securely.

Responsibilities

• Lead development of key features from concept through release, taking full responsibility from early design discussions to testing and deployment.
• Build and improve the C.Email mobile application using React Native (Expo + CNG).
• Enhance app performance and stability; address bugs and UI issues.
• Integrate and optimise cryptographic components for performance.
• Produce modular, testable, and maintainable code with clear documentation.
• Create and maintain automated testing frameworks (unit, component, and user simulation).
• Work with blockchain engineers on integrations related to data backup and key management.
• Participate in daily stand-ups and code reviews, contributing ideas and best practices.

Qualifications

• Extensive experience with React Native and TypeScript.
• Strong background in building automated test suites — unit, component, and user-simulation.
• Solid understanding of mobile-first architecture (local storage, offline-first workflows).
• Experience in startups or small engineering teams (Series A/B or pre-VC).
• Demonstrated ability to take ownership of product areas or features.
• Exposure to email protocols and standards (MIME, Gmail API) is beneficial.

Required Skills

• React Native (Expo) – advanced development and optimisation.
• TypeScript / JavaScript – daily use with strong competency.
• Kotlin / Swift – for native modules.
• Go – used in cryptographic components.
• C++ – for performance and integration-related tasks (secondary).
• GCP / AWS (basic) – setup and management of light infrastructure (SES, Lambda, Redis, RDS, EC2 autoscaling).
• Understanding of cryptographic concepts (key exchange, signing, encryption).

Preferred Skills

Familiarity with email standards and protocols (e.g., MIME, Gmail API).

What's Next?

• Talent Acquisition Interview (30–45 minutes) – an introductory call to learn about Certonymity's mission and your background.
• Practical coding exercise (60–90 minutes) – a live coding session with our CTO and a Senior Engineer based on a task we'll provide.
• Final Stage Interview (30 minutes) – meet our CEO and founder to discuss the role and company in more depth.