Back End Developer (m/f/d)

Join a multidisciplinary team shaping the future of secure digital identity in Europe. You’ll play a key role in designing and building the backend architecture of a high-trust digital wallet solution used across regulated, privacy-sensitive domains.

Key Responsibilities :

• Contribute to the architecture and implementation of the wallet’s backend services, including : Remote trust anchor (Cloud HSM) integration, Wallet and Credential lifecycle, Vulnerability management, System telemetry and statistics
• Design and implement secure, scalable, and reliable backend components, focusing on quality and resilience.
• Develop and maintain test suites across system levels, including functional, load, and performance testing.
• Evaluate and evolve existing components, replacing or refining them where needed to meet new security and scalability requirements.
• Collaborate closely with mobile / backend developers, security engineers, and architects in an agile, international team, working across German and EU government bodies and supporting organizations.
• Contribute to concise and clear technical documentation for internal processes, certification efforts, and public specifications.

What we’re looking for :

• Proven ability to deliver value in high-stakes, regulated environments, with a strong focus on backend systems that prioritize security, scalability, and compliance
• 10+ years of backend development experience, including 3+ years of Kotlin , designing and building robust, scalable, and secure REST APIs
• Deep knowledge of modern cryptography , secure protocol implementation, and identity management standards (e.g., OAuth2, OpenID Connect, Verifiable Credentials)
• Strong security mindset with hands-on experience building and reviewing security-sensitive applications , conducting threat modeling, and mitigating common web / API vulnerabilities
• Skilled in relational database design and SQL query optimization, ensuring performance and reliability under high load and complex transactional scenarios
• Experienced with s calability planning, load testing, and backend analytics, enabling insight-driven performance tuning and operational resilience
• Active contributor to the open source communities , including leadership in public technical discussions, issue triage, and contribution to standardization efforts
• Comfortable working in DevOps environments , collaborating closely with ops teams to improve infrastructure, deployment pipelines, and observability across environments
• Excellent communicator, able to bridge the gap between technical depth and practical decision-making, whether through design docs, code, or team discussions

Bonus Skills :

• Experience with Digital Credentials / OpenID / OAuth / Verifiable Credentials
• Knowledge of Hardware Security Modules (HSMs) and cryptographic key management
• Familiarity with device attestation mechanisms like Play Integrity and iOS DeviceCheck
• Hands-on experience with DevOps , CI / CD pipelines , and cloud-native operations

Benefits :

• Flexible working hours and remote work options.
• Access to conferences, team events, and a supportive work culture.