You have experience, a broad view, and deep knowledge – and you have great ambition?
You've just found your door.
We are looking for a hands-on Lead Java Developer who is ready to take over one of our teams. As the Lead, you will shape the team and take it to the next level. You will be deeply involved in defining how things will run.
Responsibilities
Development and Product
Transforming and creating a containerized microservice architecture in Java (or other languages)
Developing new products while combining legacy and monolithic Z1 software with new containerized versions
Renovating, rebuilding — and making it shine
Integrating legacy software components (monoliths) into new product solutions
Proactively planning and developing Z1 products with your team
Finding new paths and solutions to strengthen our market position
Alignment with Other Teams
Aligning your work with other R&D teams to ensure a smooth fit in the overall architecture
Being part of a cross-functional team that isn't afraid to explore new technologies or thought patterns
Team Building and Leadership
Helping develop the team to the next level
Coordinating your team effectively and understanding its capabilities deeply
Mentoring and guiding team members to deliver the features and results our enterprise customers expect
Miscellaneous / Strategic Thinking
Analyzing blockers or issues in the development strategy — and preventing them before they happen
Qualifications
You have a modernization mindset: turning complex legacy systems into clean, maintainable architecture
You have successfully worked and led in a development team for at least 7 years, delivering solutions and products together
You have at least 5 years of practical experience working with Java. We primarily use Java 21
You have deep knowledge and understanding of software architectures such as monoliths and microservices
You have experience with security topics such as PKI, S/MIME, OpenPGP, X.509 certificates, and PGP keys
Ideally, you already have knowledge of Email, SMTP, JavaMail, and BouncyCastle
You demonstrate professional proficiency in both English and German (C1 level or higher).
You are proficient with the following technologies:
Java: Java 21
Linux: Basic proficiency in Linux commands
Shell Scripting: ANSI Shell, Bash
Frameworks: Spring MVC, Spring Boot, Spring Data, Spring Integration
Message Brokers: NATS / RabbitMQ / Kafka
Containerization: Docker, Kubernetes
Microservice Design: Experience with microservice architectures
Monoliths: Experience working with monolithic applications
Build Tools: Gradle
Software Testing Methodologies
Knowledge of Smart Cards or Hardware Security Modules is not required but is a great advantage.
Our offer:
Flexible working hours and home office possible
Mobility: free Germany ticket, job bike leasing or car parking
Allowances for food (e.g. Lieferando) and internet in the home office
Benefits in the office: Roof terraces & green courtyard, organic fruit and drinks, parcel acceptance
Get-together: pizza Friday in the office, regular team events, big summer party
Why Zertificon?
Zertificon stands for securing digital business. We develop trusted IT security solutions "Made in Germany" – built for businesses that value both protection and usability.
Independent & committed: For over 20 years, we've built secure communication tools – as an owner-managed company with a clear stance
Purpose-driven: We believe that digital communication must be secure and free. If you think Edward Snowden did the right thing as a whistleblower, we might just share the same values. As a sign of our support, we donate €1,000 to an organization that supports Edward Snowden for every new hire who mentions him in their application
Hands-on excellence: We take on complex challenges because we can. Our in-house experts are top-tier – even external specialists often learn from us. When we want the best, we build it ourselves
Agile by conviction: We think fast, act pragmatically, and improve continuously. No bloated processes, no "that's just how it's always been done." Initiative is welcome – but of course, it will be challenged, and not every idea will make it through unchallenged
Security that works: We build software that's not only secure, but actually usable – not just for large enterprises with dedicated highly skilled IT teams, but also for small and mid-sized businesses that need strong security without the complexity
Diverse & international: Our team of 120 people from 30+ countries shares one mission: making secure digital communication easily accessible to businesses of all sizes
If that resonates with you, we'd love to hear from you.
Want to know more? Please have a look at our Work at Zertificon page:
Questions?
You can reach our HR team