✉️ [jim.mavrommatis@gmail.com](mailto:jim.mavrommatis@gmail.com)
🌍 [LinkedIn](https://www.linkedin.com/in/dimitrios-mavrommatis)
🌍 [GitHub](https://github.com/slowr) | [GitHub Work](https://github.com/dmavrommatis)
# **Dimitrios Mavrommatis**
I'm a software engineer with over 10 years of experience in backend development and site reliability engineering. I've led teams in architecting scalable, high-performance systems, particularly focusing on Kubernetes and multi-cluster environments. I'm skilled in strategic leadership and mentoring, and I'm passionate about delivering cost-effective and resilient systems. I'm currently looking for opportunities where I can lead backend and infrastructure teams to build scalable systems that drive business success.
## **Experience**
### **NS1 (acquired by IBM in June 2023) – Lead Backend/SRE Engineer**
**December 2020 – Present | Remote, Netherlands**
- **Kubernetes Subject Matter Expert**: Led the automation and standardization of Kubernetes infrastructure across 30+ clusters, supporting multi-region deployments. Pioneered the rollout of NS1’s multi-cluster, multi-region Kubernetes setup, improving deployment speeds by 50% and reducing production issues. Achieved IBM's Level 3 Expert badge as Kubernetes SME.
- **Cost Optimization**: Implemented build and test optimizations, saving $10k/month in operational costs by migrating from docker-compose to skaffold/Kubernetes and reducing CI build times by 80% (from 45 minutes to 9 minutes) with advanced caching and parallelization techniques.
- **Database Optimizations**: Achieved 100-1000x performance improvements through database query optimizations and zero-downtime migrations to different database systems such as Clickhouse for analytics. Increased data integrity by implementing the Outbox pattern for transaction guarantees in high-throughput systems. Customer tickets about slow queries dropped to zero.
- **Global Product Architecture**: Architected and deployed a global [HTTPS redirect service](https://www.ibm.com/blog/announcement/making-https-redirects-easy-with-ibm-ns1-connect/), managing over a million active certificates with end-to-end development in Go and Kubernetes, integrating TLS protocols, observability tools, and stringent security measures for robust global reach. This new product allowed all of our customers to migrate from external HTTPS providers to our own, which opened new market opportunities and increased revenue.
- **Service Lifecycle Ownership**: Managed the lifecycle of critical backend services, ensuring zero service disruptions in high-demand production environments while adding new features.
- **Automated Certificate Lifecycle**: Developed a fully automated certificate issuance and renewal system leveraging ACME protocol and DNS01 challenges, enhancing security and eliminating manual certificate management time.
- **Team Leadership**: Led a 5-member cross-functional development tooling team, driving operational efficiency improvements through targeted infrastructure optimizations, leading to enhanced backend system quality and reduced engineering bottlenecks.
- **Cross-Functional Collaboration**: Collaborated with product and engineering teams to align infrastructure improvements with business goals.
- **Mentoring & Interviewing**: Participated in the interviewing process that helped grow our team by 5 members. Mentored multiple engineers of all levels and received 27 recognitions from IBM's recognition platform.
- **On-Call Rotation**: Participated in on-call rotation and served as incident commander on 20+ SEV1 incidents. Mitigated most of the incidents in less than an hour.
---
### **Elsevier – Senior Software Engineer**
**April 2020 – December 2020 | Amsterdam, Netherlands**
- **Leadership and Mentorship**: Mentored junior engineers and guided the team on architectural decisions, contributing to a collaborative and high-performing team culture.
- **Microservices Architecture Transformation**: Directed the migration of a monolithic application to a microservices-based architecture, improving scalability and development velocity.
- **CI/CD Pipeline Setup**: Architected a comprehensive CI/CD pipeline for the front-end guild, reducing deployment errors and increasing feature release speed by 40%.
- **Performance Optimization**: Identified and resolved critical performance bottlenecks in the development process and application stack.
---
### **Adyen – Software Engineer**
**April 2019 – March 2020 | Amsterdam, Netherlands**
- **Build Optimization**: Led the optimization of build and CI/CD pipelines, achieving an 85% speedup and increasing development velocity.
- **Architectural Modernization**: Directed the migration from a monolithic architecture to microservices, enabling scalability and improved fault tolerance.
- **Kubernetes Administration**: Administered the development Kubernetes cluster, providing strategic input on infrastructure scaling and security improvements.
---
### **Open Networking Foundation – Software Engineer**
**June 2017 – March 2018 | Menlo Park, California**
- **SDN Project Leadership**: Led a team in developing open-source SDN applications, including pioneering work on xRAN and FPC Agent.
- **Full Lifecycle Ownership**: Managed the entire lifecycle of SDN prototype applications, from architecture to deployment, which were presented at Mobile World Congress.
---
### **Telecommunications and Networks Laboratory – FORTH-ICS – Research and Development Engineer**
**June 2015 – June 2017 / March 2018 – April 2019 | Heraklion, Greece**
- **Open-Source Leadership**: Led open-source projects in telecommunications and networking, presenting innovations at international conferences.
- **Microservices Architecture**: Designed and implemented microservices-based systems for high-performance network applications.
- **DevSecOps**: Managed secure, production-ready tools for research deployments, ensuring operational integrity and security.
- **Database Systems Management**: Optimized and monitored complex distributed databases for high-volume data applications.
- **ARTEMIS Project**: Developed [ARTEMIS](https://github.com/FORTH-ICS-INSPIRE/artemis), an open-source tool for real-time defense against BGP hijacking, leading to the formation of a startup that was later acquired by Cisco.
---
### **Contractor – Full Stack Developer**
**September 2012 – June 2015 | Heraklion, Greece**
- **Platform Migrations**: Led multiple platform migrations to React Redux, improving performance and maintainability.
- **Security Expertise**: Conducted penetration testing and red team assessments to improve client system security.
## **Education**
### **Master of Science in Computer Science**
University of Crete, GPA: 8.79/10.00 | 2015 – 2018
Thesis: [ARTEMIS](https://bgpartemis.readthedocs.io/en/latest/) – An Automated System against BGP Prefix Hijacking
### **Bachelor of Science in Computer Science**
University of Crete, GPA: 7.62/10.00 | 2011 – 2015
Area: Distributed and Parallel Systems
Thesis: Transparent Failure Recovery and Elastic Load Balancing on [Tyche Protocol](https://www.researchgate.net/publication/269294201_Tyche_An_efficient_Ethernet-based_protocol_for_converged_networked_storage), (**C kernel module**)
## **Skills Summary (not exhaustive)**
**Languages**: (**expert**) Go, Python, C, Shell; (**proficient**) Java, JavaScript, C++; (**basic**) Rust, Groovy, Kotlin, CUDA
**DBMS/Queues**: Postgres, Clickhouse, Mongo, Redis, Kafka, RabbitMQ, DynamoDB, LMDB, BadgerDB, MySQL, SQLite
**Tools**: ArgoCD, Terraform, Ansible, ELK Stack, LGTM Stack, Docker, Kubernetes, Jenkins, Vault, Vagrant
**Protocols**: TCP/IP, BGP, DNS, TLS, HTTP/2, RESTCONF, WebSocket, NETCONF
**Other**: Microservices Architecture, CI/CD Pipelines, GitOps, AWS Cloud
**Open-source Contributions**: [Kubernetes](https://github.com/kubernetes), [Docker](https://github.com/docker), [Jenkins](https://github.com/jenkinsci), [ONOS](https://github.com/opennetworkinglab/onos), [GoogleContainerTools](https://github.com/GoogleContainerTools), [Hasura](https://github.com/hasura), [Celery](https://github.com/celery), [TektonCD](https://github.com/tektoncd).
References upon request