Hi. I'm Julian Seiss.
Software Architect, Technical Lead, and Developer from Cologne. I design systems, lead teams, and build pragmatic solutions.
Let's work together
Pragmatism is key
With over 18 years in software development, I help organisations design robust systems and lead engineering teams through complex projects. Whether it's architecting a cloud migration, writing production code, or coaching teams to deliver with confidence - I focus on outcomes that last beyond my engagement.
Software Architecture
I design and build scalable, maintainable systems — from domain modeling and service decomposition to hands-on implementation. I make the technology decisions that shape a product's future and write the code to back them up.
Java/Spring, Kafka, Kubernetes, microservices, domain-driven design
Technical Leadership
I guide engineering teams through complex projects — owning delivery, making architectural trade-offs, and building the processes that let teams ship reliably. I bridge the gap between strategy and execution.
DevOps, CI/CD, Infrastructure as Code, Terraform, GitHub Actions
Coaching & Communication
I help teams grow through pair programming, knowledge sharing, and hands-on mentoring. I translate between technical and business stakeholders, making sure everyone moves in the same direction.
Pair programming, mentoring, stakeholder communication, agile facilitation
AI-Augmented Delivery
I integrate AI tools into development workflows to accelerate delivery without sacrificing quality. From code generation to automated reviews, I help teams ship faster while maintaining engineering standards.
AI-assisted development, code generation, automated reviews, agentic workflows
Selected projects
Core Platform Re-Implementation - Scalability & Performance
A 10-year-old core system at the heart of the customer's ecosystem had stopped scaling, with poorly performing legacy code driving recurring production incidents. I built the business case for a full re-implementation and led the architecture — a scalable, event-driven design on Java, Spring Boot, and Kafka. Close collaboration with the Product Owner turned the rewrite into an opportunity: entrenched legacy features were challenged and long-requested capabilities finally unblocked. An AI-assisted implementation strategy accelerated delivery without compromising quality.
Java/Spring Boot, Kafka, event-driven architecture, scalability, performance, AI-assisted development
Dual-Cloud Initiative - AWS & Azure
As a co-architect in a dual-cloud initiative, I helped make a microservice ecosystem cloud-agnostic (Kubernetes over AWS ECS, Kafka over Kinesis) so it can run on both AWS and Azure in parallel. I contributed to a domain-vertical decomposition that replaced tangled service dependencies with clean, asynchronous communication between bounded contexts. The result: no vendor lock-in, deployment to both cloud providers, and independent scaling per domain.
Java/Spring, Kubernetes, Kafka, AWS, Azure, multi-cloud, Docker, Terraform, microservices
Enterprise Identity Management - Keycloak Rollout
A fragile custom-built IDM was replaced with Keycloak under my architectural lead, backed by a Salesforce-sourced user provider I developed from the ground up. The rollout spanned 20+ countries across B2B and B2C, supported by a monitoring and alerting pipeline, security practices including regular threat modeling and penetration testing, and hands-on incident response to keep the system running smoothly.
Keycloak, Java, Salesforce, OAuth 2.0/OIDC, ELK, Docker, security assessments
Let's work together
Looking for a Software Architect or Technical Lead for your next project? Let's talk.