Krzysztof Ciesielski
Head Of Security at SoftwareMill
Lublin Voivodeship, Poland
Summary
🤩
Rockstar🎓
Top SchoolKrzysztof Ciesielski is a Head of Security and seasoned software engineer with 14 years of experience building robust, testable systems from backend stream processing to frontend UX. Based in Lublin Voivodeship, Poland, he brings deep Scala and Java expertise from a long tenure at SoftwareMill and prior roles delivering JEE integrations for banking and healthcare. He has hands-on open-source experience contributing to high-profile projects like Alpakka Kafka (reactive Kafka connectors via Akka Streams) and Tapir (self-documenting API codecs), with a clear emphasis on correctness through Reactive Streams TCK tests and enhanced time-type codecs. Technically grounded yet leadership-focused, he blends security stewardship with practical engineering—driving refactors, CI-backed testing, and maintainable architecture. Notably, his background spans both backend stream-processing internals and Angular front-end improvements, reflecting a rare full-stack curiosity in an engineering-security leader.
14 years of coding experience
17 years of employment as a software developer
Postgraduate, Java Software Design and Development, International exchange, Informatique (Computer Science), Master, Computer Science (Computer Technologies), Postgraduate, Java Software Design and Development, International exchange, Informatique (Computer Science), Master, Computer Science (Computer Technologies) at Uniwersytet Marii Curie-Sklodowskiej w Lublinie
Uniwersytet Marii Curie-Skłodowskiej w Lublinie
Polish, French, English
Github Skills (29)
unit-testing10
javascript10
back-end-development10
apidoc10
testing10
kafka10
java10
scala10
javas10
api10
front-end-development10
akka-streams10
producer10
reactive-streams10
customer10
Programming languages (12)
Github contributions (5)
akka/alpakka-kafka
Dec 2014 - Nov 2020
Alpakka Kafka connector - Alpakka is a Reactive Enterprise Integration library for Java and Scala, based on Reactive Streams and Akka.
Role in this project:
Back-end Developer & Test Automation Engineer
Back-end Developer & Test Automation EngineerContributions:23 releases, 378 commits, 110 PRs in 5 years 11 months
Contributions summary:Krzysztof primarily worked on implementing a Kafka consumer and producer in Scala, focusing on building a reactive Kafka connector using Akka Streams. Their contributions included creating a `KafkaActorSubscriber` and a `KafkaGraphStageSource`, demonstrating a strong understanding of stream processing. They also added tests using the Reactive Streams TCK, revealing a focus on testing the connector's functionality. Furthermore, they refactored the consumer and producer setup to use properties, and implemented features like manual offset committing.
enterprise-integrationkafka-connectorconnectorstreamsplay-framework
softwaremill/bootzooka
Mar 2013 - Apr 2017
Simple project to quickly start developing a Scala-based microservice or web application, without the need to write login, user registration etc.
Role in this project:Front-end Developer
Front-end DeveloperContributions:2 reviews, 164 commits, 10 PRs in 4 years 2 months
Contributions summary:Krzysztof primarily contributed to the front-end of the application, focusing on the implementation of Angular directives, filters, and unit tests. They refactored and renamed Angular directives, extracting them into separate files for better organization. Furthermore, they adapted the in-browser Jasmine runner to the new directory layout. Their work demonstrates a focus on improving the quality and maintainability of the front-end code.
developingskeletonregistrationweb-applicationplay-framework
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