Identity and access
Services that extend what an identity provider offers out of the box, and self-service tools for managing and monitoring them, built on OAuth2 and OpenID Connect.
I turn tangled business processes into backends that just work.
Maciej, senior software engineer. Ten years of building commercial software in Java, Kotlin and Spring, mostly on identity platforms, event-driven systems and e-commerce integrations.
I choose the architecture for the business problem, not the other way round. My work starts well before the first line of code: understanding what the business really needs, questioning the requirements and designing a solution the team can build, run and evolve.
- CurrentlySenior Software Engineer at Kingfisher, on the Screwfix Customer Account team
- Before thatSeven years at Apollogic, as senior software developer and tech lead
- Daily stackKotlin, Java, Spring Boot, PostgreSQL, Kafka
- Beyond codeTechnical interviews, onboarding, internal talks. I worked at university before moving into industry.
What I work on
Three areas where most of my projects have landed, usually at the point where they meet each other.
Event-driven systems
Kafka and RabbitMQ pipelines, domain-driven design, CQRS and event sourcing where they suit the domain, and the less glamorous parts that make them safe in production: idempotency, the outbox pattern, retries, ordering and race conditions.
Commerce and integration
Developing custom e-commerce systems and integrating them with SaaS providers, so that in-house code and third-party platforms work as one product.
Career, as an event log
My career so far, replayed from offset zero. Each entry is something that changed the state of what I can build.
consumer at head, offset 3
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0
ScientificResearch 2015 to 2017
Lecturer at Adam Mickiewicz University in Poznań, Poland, building computer simulations of social and economic systems. Where I first learned to treat a system as a stream of state changes.
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1
JoinedApollogic 2017 to 2024
Seven years at Apollogic, a software house, growing into senior software developer and tech lead roles: owning architecture, guiding teams and working directly with clients.
substream: apollogic.projects5 events
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1.0
CommerceShipped
Developed e-commerce platform modules for many clients, built a delivery monitoring and management platform for a large consumer electronics retail chain, and extended CMS systems with custom modules.
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1.1
DevicesMonitored
A Java and Spring backend that managed and monitored a fleet of thousands of devices around the world, first on Azure and later on AWS, collecting sensor data and storing it for analysis.
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1.2
TestManagementBuilt
A centralised test management system for the European Space Agency, built to standardise and speed up the testing done by the agency's subcontractors.
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1.3
MigrationPlatformLed
Led a self-service platform that sped up and partly automated moving nearly 600 applications from many custom CIAM systems to Microsoft Entra ID.
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1.4
EInvoicingIntegrated
A service integrating a large legacy CMS with KSeF, Poland's national e-invoicing system, automating how invoices are sent and received.
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2
JoinedKingfisher 2024
Senior Software Engineer on the Screwfix Customer Account team, working across customer accounts: developing the CIAM system and the microservices customers use to manage their account data.
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3
StillConsuming now
Interviewing and onboarding engineers, giving internal talks, and writing about technical topics.
Writing
All articles on MediumSide projects
- Event-sourced ticketing systemA ticketing system built on event sourcing and CQRS, with a Java and Spring Boot backend and a Vue.js front-end.
- JPA ORM benchmarkJMH benchmarks comparing the performance of JPA implementations, Hibernate among them.
- Agent-based simulationsSmall agent-based modelling experiments that show how simple rules for individual agents produce complex, emergent patterns.
Toolbox
What I reach for, roughly in order of how often. Go, Python and TypeScript are for tooling and glue, not the main product.
- Main languages
- Java (versions 8 to 21), Kotlin
- Supporting languages
- Go, Python, JavaScript and TypeScript, SQL
- Frameworks
- Spring Boot, Quarkus, JPA and Hibernate
- Data
- PostgreSQL, Microsoft SQL Server, MongoDB and other NoSQL stores
- Messaging
- Kafka, RabbitMQ
- Design
- Event-driven architecture, DDD, CQRS, event sourcing, data-oriented programming, functional programming
- Identity
- Keycloak, PingOne AIC, Entra ID, OAuth2, OIDC, JWT
- Cloud and runtime
- AWS, Azure, Docker, Kubernetes
- Delivery and observability
- GitLab CI/CD, Testcontainers, Datadog, Prometheus, Grafana